Square has secured at least $10M in funding (http://www.crunchbase.com/company/square) and are pretty far along from what I can tell. That said, there's almost always room for competition, especially in the payment gateway market. If you think you can make something that is better/cheaper/simpler/etc., I'd say go for it (since you've already been working on this for the past few months). Find a partner to help you out and if you need money, try pitching to local angel investors. If you can seriously compete with Square (and convince them of that), it shouldn't be hard to get some kind of seed funding.