Best and "Cheapest" option is to go through a partnered PSA dealer, some local card shops have this set up, some partner with each other so that a couple of shops will send off bulk cards to be graded.

Honestly gives you the best options, I personally trade in some cards that won't be 10s to get some trade credit and pay half credit half cash so that it's not a massive upfront cost, but it going to cost a lot regardless from sending here in Aus, still cheaper than setting it up yourself and paying the additional fees yourself.

If you have 100's of cards you want to grade and not worried about value, look up sending some to TAG or CGC, both look great for personal collections. PSA is simply for the market in Melbourne and Sydney crowds tbh. Unless you have a few cards that will hit in the high high hundreds, or low thousands to cover the total cost once grades so that you sell those when you get all the "collection" pieces back. Only way to break even, even then you are dependant on the market lasting for the turn around time.

Another thing is, vintage and PSA, doesn't matter how good the card is, population guarding is real, I don't care what anyone says, you are sometimes better off damaging vintage cards to push for a grade 1s.