I know I've seen some on linentablecloth.com. We didn't get sequins, but we did get our tablecloths from there very cheap. If you can't get sequin tablecloths cheap, maybe regular tablecloths with sequin table runners instead?
I got sequin table runners off Ebay super cheap. I believe I saw some full sequin table clothes when I was looking.
Check FB Marketplace! I had a round 120" gold sequined tablecloth for my sweetheart table, and we got it from Marketplace for only $25! I searched for over a month to find one at a good price, though.