Please shoot my (cryptocurrency) idea down

Hi, r/Entrepreneur!

I'll keep it short. I want to create a payment gateway for cryptocurrencies. The idea is that I would create a website plugin for eCommerce sites that would accept cryptocurrency from customers, convert it to fiat, and transfer the fiat to a vendor.

I am aware that the crypto<->fiat conversion is legally messy. I made a post over on r/legaladvice if you'd like to check it out.

https://www.reddit.com/r/legaladvice/comments/7vsdmf/what_regulations_should_i_be_aware_of_if_i_intend/

My question is this: Am I out of my depth here? It seems that if crypto<->fiat conversions were easy, they would be everywhere already. Instead, very few crypto exchanges allow the service. From what I can tell, it is very difficult to meet the regulations set down by FinCEN and qualify as a bona fide MSB. But what's so difficult about it? Not saying it isn't, I just don't know what the catch is. FinCEN has a form you can fill out to file as a MSB. What happens after I fill out the form? Can I start building the product?

I'm just a regular dude with a decent paying job. I don't have $50k+ lying around, I just want to build a plugin. I have a free consultation with a lawyer lined up, but before I meet with him, I'd like to know if I'll be wasting his time or not.

I've never incorporated a business before, though I've always heard it's not too hard. But taking into consideration KYM/MSB regulations, would I need thousands of dollars and a team of lawyers to implement this idea, or should I take a shot at it?

Thanks!