[L473ncy]

Second link is a go but like Styrak said don't order receivers from out of country so the first link you should take a pander through the retailer section to find what you need.

If I were in the same position as you though I would honestly aim at spending less than $50 to make it perform well.

Some things might be "free" fixes like if you have stuff in your work shop/garage like lithium grease and o-rings (that are the right size) for whatever reason. Others might be $10 fixes plus time to take it apart and put back together like the compression unit (cylinder, piston head, etc.).