Launch contests are a great way to give affiliates further incentives to promote your product or service. I believe you don't need $10k sitting there for your launch prizes if you have done your testing and homework beforehand.
If you have worked out your EPC and do a few stats to see how many sales you will need for a $10k contest then you will find out if you can run one or not. If you have to scale down that isn't a big issue.
You can also offer a contest that gives incentives to all affiliates and not just those who land in the top ten. That is get X amount of sales and recieve a $50 itunes/amazon gift card etc etc. And as they go higher the better the prize can be. If you knew your launch would be massive with big hitters already on the table then you could add both.
Also product launches with a pre-launch phase normally add a smaller competition for the pre-launch. I.e. send a certain amount of leads and get a prize or a major prize at the end of the contest. This will normally happen when initial testing has taken place so they know how much they will earn per lead generated.
If you do beta testing you will have these results and will be able to determine what kind of contests and prizes to include.
Another area to think about is the actual prizes. Will it be a cash contest? Or actual tangible items? Most of the MMO launches these days whip out cash prizes or 'tech' prizes like iphones, ipads, netbooks etc etc. Change it up a bit and really think about the prizes. Possibly a paid holiday worth $5k for #1, remote control helicopter/cars, awesome seats for a concert or sporting event etc etc etc. You can always equate your prizes to a cash amount if the winning affiliate would rather the cash! This also comes in handy if they are an international affiliate.
There are many more things you can offer that don't have to be cash etc but will make/earn money in the future. I.e. sending out their promo to your mailing list, creating content for them if you are a gun copywriter or have one on your staff, graphics, video, interviews etc etc. It all adds up and doesn't have to initially be about $$$.
Others will hopefully have some more ideas to contribute!
Hope this helps.
nathanj