Don't bother competing with these. You would need a hell of alot more than $3,000 to develop the site in my opinion. When you're dealing with money on that kind of level, I think your legal costs will cost more than $3,000. Not to mention the HUGE amounts Paypal spend on advertising, mostly helped by the millions of eBayers, they have a constant source of customers. Oh, and Google Wallet (if it's released) will probably have the equivalent of millions and millions of dollars worth of advertising spent on it. Considering when money is concerned, trust and reputation is 10x more important, people would pick Google over a brand new company any day.