Actually max you'd need would be a shade under $5,000 only if you bought something way in the money for binaries.
Ideally, I don't like risking more than 1% of my available equity, in which case, I'd need $50,000. (I included one too many zeros before.)
Look, I hope you're right about your chances with Nadex from demo. But the consensus from past threads on them was that the spreads are so horrible that your win rate has to be very high. And if you're that good, a far more fair and profitable game would be trading vanilla options with 1 penny spreads at volume and volatility levels sufficient for your operations.
Who offers vanilla options? I have been looking for an alternative to Nadex since February 22nd, but have yet to locate one. A contributor to these forums wrote that Cantor Exchnage and CBOE are the only other CFTC regulated binary options exchanges (a requirement for USA citizens) but it turns out that Cantor Exchange just recently discontinue listing Forex and gold binary option instruments (at the end of March) and CBOE offers only two binary options, neither of which are Forex—my specialty. I also looked into financial betting via betonlin.ag, but they are either unwilling or unable to provide me with clear, definitive information regarding their withdrawal policy with respect to financial betting winnings, which I regard as a big warning sign, and will therefore have nothing to do with them. When I look up vanilla options online, all I get are definitions and descriptions. Correction: It looks like some outfit called Quedex offers them, but not for USA citizens. The same is true of EasyMarkets and London Capital Group. Were I to continue this search (which I'm not) I imagine I would once again confirm that, as a U.S. resident, Nadex is, practically speaking, my only choice when it comes to binary options.
Every broker offers "vanilla" options, those are what we call plain old puts and calls. You're correct that now only Nadex offers forex binaries to U.S. customers. Binaries are generally called "exotics" vice "vanilla" for regular options. One of those lingo things that makes about as much sense as "American" vs "European" expiration.