Well, I think I would do both. When you're at a swap meet and looking at a block it might be handy to have a sonic tester to see if it would a good candidate. I not interested in buying every block I see to find a good one. I have no problem paying my machinist (Hughes Engine) to do a sonic test.
This post has nothing to do with cost but rather what have other experienced with their 360 blocks and I guess you and I would differ on the term "cheap pistons"
