I've currently got 400 45s on ebay, including a lot of northern soul, R&B, popcorn, funk, crossover, modern, etc. Have a look, nearly all listings start at just $5.99: https://www.ebay.com/sch/kidinquisitive/m.html

I also have very reasonable shipping rates (below actual cost):  International first class shipping for 1 to 3 45s is $11. More than 3 45s costs $18, no matter how many you win! 

Final day on these, thanks again for looking: https://www.ebay.com/sch/kidinquisitive/m.html