My Update:
I was also on a conference call with a lawyer (Ray) and I am inclined to become his client. The other lawyers I spoke with are more experienced with BTC but wanted retainer and be paid on hourly bases, while Ray's 40% is high, that is only 40% above current offer of $5,600 USD. Also, issue is not as much BTC related as contract related to be paid back in a form we paid which was in BTC. So I think that it's a safer choice. If I get in the end $5,600 I keep it and anything above it I keep 60%. Also there is a possibility that lawyer would be awarded fees separately from our award and in that case I keep 100%.

It is more preferable to me to not send good money after bad and I am willing to keep 5,600 + 60% than put additional $10k in retainer on a line.

If you would like to be represented by a same lawyer I recommend you contact him ASAP yourself.
http://www.gallo-law.com/attorneys/gallo.html