Do you also have a PAL TV? Or one that can play NTSC and PAL?
The cheapest by far is one that goes into a computer. Unlike computer DVD drives, computer Blu-ray drives do not lock into the first region code, so you can play from any region as long as the player software supports it.
And if you find that you don't happen to have a PAL-capable TV, just about any home computer you're likely to still be using is more than capable of doing the scan conversion so it displays (and displays well) on a NTSC or other ~60Hz TV.
You may be able to find "pirate ROMs" to flash your existing Blu-ray player that supposedly enable playback of out-of-region discs. If you can find one for your player for free, that's the cheapest you can getunless it renders the player useless.

Try out players in a store. I suspect some that aren't Sony will play PAL content. Start with the cheapest and work up. Look for the N/P button on the remote (as I think I suggested before).
Try a region-free PAL DVD as well.