Would my mare/filly On thin Ice breed well to a seacritat son. excuse spelling 
To be honest, there’s not a whole bunch to go on, at least on the dam’s side. None of her 1/2 sibs have thrown anything of racing age. Her dam seems to throw allowance horses when crossed with less popular studs. There’s nothing to suggest it would or would not be a good match.
Something that you may find helpful is the hypo-mating feature: http://www.finalfurlong.org/hypomating.php
When stud shopping, I look for proven producers (breed rankings help with this, found at: http://www.finalfurlong.org/breedrankings.php?show=s&active=y), or a new stud with an awesome race record that complements what my horse has done or has potential to do (e.g. Lonesome Glory means jumps, so I breed my Lonesome Glory mare to Takemetohollywood, who was an awesome SC’er).
I also look at what my horse’s 1/2 sibs, to see if those with different sires have done better. For example, my mare Fleeting Beauty has a 1/2 sib whose sire is Affirmed. This 1/2 sib kicked butt on the track, so I bred Fleeting Beauty to Affirmed before he retired. Or, if the 1/2 sibs are old enough broodmares to have foals on the track, I check out who they’ve been bred to and if they’ve had any success with the cross. If there’s a SW that these 1/2 sibs have thrown, I consider breeding to the same stud that resulted in that SW’ing cross.
Unfortunately, this last method only works if your mare has 1/2 sib broodmares that are old enough to have foals on the track.
You’ve got 4 Secretariat sons to choose from. Of these, only one has enough foals to be ranked.
NCh. Secretary is Bronze rated. He’s thrown a couple very nice foals, and a lot of money earners (allowance ponies), regardless of the quality of the mare. So, barring a genetic freak, your foal would probably at least earn back the stud fee for you. Stud Fee is $10,000.
NCh. Government Secret has not yet earned a rating. He’s got a couple winning 3yos and a couple unraced 2yos. He’s only won 4 stakes wins, but that was back in the day when horses ran less often, and hence Stakes races were a little more competitive. He’s got some definite potential, but for the price ($15,000), it’s a bit more of a gamble, especially if you’re on a budget.
GCh. Secretsarebound looks to be your bargain stallion. His stud fee’s only $1,000 and has earned himself 7 stakes wins. You should note that he’s not breeder’s cup nominated, which probably won’t matter too much unless your foal is a super star. No foals to race, so nothing to go on there. However, if the foal’s anything like his dad, you’re looking at a very late bloomer.
ICh. Stressed looks to be another decently priced stud at $5,000. He’s in his first year as a stud, so no foals to go on. 10 stakes wins to his credit, he may be worth the extra price. Plus, he’s nominated for the Breeder’s Cup.
Hope this helps. Hypomating is your friend.
Oh, on another note I wouldn’t consider breeding On Thin Ice anytime soon. She looks to be a very nice and consistant runner and would earn you WAY more money than breeding her at this point in the game. Also, she has yet to meet any of the requirements for broodmaredom (check the FAQ on the requirements), aside from being a filly. Good luck with her.
Breeding is really fun, but it can cost you a lot of money…you’re paying for the stud fee, the broodie for the rest of her life, and for the foal as you raise it for those first couple of years before it can race and (hopefully) attain riches and glory and fame for you.
With all due respect, I would encourage you to keep racing On Thin Ice. She looks like a nice racer so far.
If you’re lucky, you may be able to pick up a broodmare in foal at auction (though the prices for broodies can vary widely, and I think the average price is still around 40-50k). But, unless your stable starts picking up some good earnings, I would recommend that you wait for the foal auction at the end of the year; you can pick up a weanling or yearling for a price that is usually fairly affordable, and still get that feeling of pride when you get to watch ‘your’ baby race after a year or two.
Hopefully you will do well enough to be able to afford breeding soon, but breeding horses is really a luxury, and you need to take care that you can afford to do it.
What about Temptation? All the others are in Oz so I have changed plan
Since your mare needs 5 more races and another 6 months before she’s even eligible to retire, I assume you’re shopping around for next year?
Even though I stand Temptation, I’ll be honest. I retired him before the higher level stallion requirements kicked in because I didn’t think he’d make it to 10 SWs. He was a pretty nice runner, but mostly I retired him because I wanted a Calypso son at stud. He’s on the short side, so with your mare’s shortness you’re not going to get a big tall runner, but I think shorter horses are more likely to stay sound, so it might work for a long-term campaigner. Temptation was primarily a turf horse, so a foal’d probably be able to do turf or dirt. He was also stronger at longer distances.
It depends on your breeding strategy. If you want a stud to complement your mare’s weaknesses then he’s certainly not a bad choice. If you want a stud that will enhance your mare’s strengths then there may be a better choice for a stud. You can check these things out by using the buttons underneath the race records for your mare and the potential stud to compare records on dirt/turf/SC and distances. That’s basically what I just did for the above 
. Especially if you’re looking at younger studs who don’t have crops racing.
Either way, I second the suggestion that you keep playing around with your mare for the rest of the year. Many FF horses have successful years as 4yos and I’d encourage you to consider keeping her running into her 4yo year unless she starts performing worse.
Good luck stud shopping.