A lot of scam sellers will claim they are selling you LeetDMA, but that's not what you're really getting. They just use the branding to help them sell their shit.
The only way to know you're getting an authentic LeetDMA card is to buy from the enigma store directly.
Yes the other cards work, but the Firmware and QA testing can be sometimes sketchy depending on who is selling it. Also you may not get any support if something goes wrong.
Otherwise, the firmware you get may not be custom (requiring an additional purchase, so you're not really saving anything), or it could be a firmware that is pooled to hundreds of users.
I had a customer (one out of hundreds) that ended up getting a DOA LeetDMA Card, and Enigma RMA'd it for him. It was really good support.
I had a few people who got AceDMA and their cards ran really slow / kept dropping out.
tl;dr - yes the cheaper cards can work, but you will have to do your homework to make sure you are getting something good -- a lot of sellers fraudulently use brand names from other providers too.