Hey! I get them from all over, eBay, Japanese sites, and buying them already graded as 10s. Its difficult as there are lots of reasons which make them really difficult to find. The values really vary, if you’re selling/buying PSA 10s at auction you can get common ones for $30 or less. Rarer ones go from anywhere from $100-350. Mint condition ungraded ones are usually $10-20.
I’m only looking for PSA 10 or mint condition ex cards, and if you have those feel free to check out my wants thread which lists the cards I need: www.elitefourum.com/t/fourthstartcgs-ex-series-full-art-wants-thread/12824/1
Glad you enjoy the scans! Its hard to show in a picture how great these look but the scans do a good job.