e-filing using Turbo Tax or Tax Cut (or any other similar SW): You pay only one time. I think ‘글쎄요’-nim is using web-based tool. In this case you don’t buy the software but sort of service so you don’t pay a penny until you file electronically to IRS (Yo uhave an option to print out and file it though the snail mail of course, but still pay the same) There can be discount coupons, so the real cost varies, but I think you may expect somewhere between $25 – $50.
As ‘tax’-nim said, you can download the form from IRS and fill it manually and send back to IRS (my penny: it may not be the cheapest way when you take the effort+time you need to put to finish into account^;