Price range to ask for used AR Ref1 and Passlabs X250?

You have many online resources at your disposal to do your research. Here are three for starters: Audiogon BlueBook, HiFi Shark and completed sales on eBay. Good luck.

If by “process” you mean selling; the good new is that you certainly have desirable products of value to sell. Audiogon would be a good place to start, if you’re considering selling everything yourself. One alternative strategy to consider is selling or trading your equipment to an entity like TMR (The Music Room). Yes, you may receive less ($) for each item but you may also have far less potential headaches/trade-offs. From experience I can tell you that NOS tubes can sell well on eBay.