Gen parts

I’ve been accumulating parts for a 16610 build to make it as Gen as possible, and I’m looking at gen dials, crystal and bezels now. I’m having a hard time finding Gen bezels (already have the insert, retainer, washer, and click spring, also have the hands, date wheel, crown and stem, all Gen.)

Next, I’ve found Gen crystal and dials on eBay, but I’m trying to A.determine a reasonable price point for each. I’ve seen crystal from $150-400ish. Dials have generally been in the high 5-almost $800 range. Most in good shape, some beat up. Also, B. Given these are higher ticket items and really define at first glance how legit the watch is, how do I ensure that they are gen, aside from staring at the details until my eyes glaze over, looking at the seller, reviews, return policy, guarantees, etc. Do all dials have etching on the back? I’ve seen some have Rolex and the crown, some have some numbers, some have a b or r, and some are smooth. Any recs for good sellers, please reach out or pm. I’ve found one in particular someone recommended before.