The Sony Betas required regular maintenance back in the day, and they don't like being left sitting unused for years on end. They are not as easy service as VHS decks, so a lot of the remaining chop shops won't accept them for repair.
Early on I was disappointed by the mediocre recording quality of VHS, and added a BetaMax. I loved my Sony SL-5800, it remains my benchmark for luxurious feel in consumer electronics, but I sold it in 1985 to pay for the first BetaHifi model SL-5200. That monster broke down so often I finally got tired of repair costs and just left the screws out of the cover, because I had to pop the hood to nudge the gear train every time I needed to rewind or eject a tape. When VHS HiFi became affordable I shifted to VHS 100% and never looked back.
Until 2006, when I needed another BetaMax to dub my remaining Beta tapes to DVD. I picked up a nice clean SL-HF500 on eBay for $150 and used it to digitize a couple dozen tapes, then got distracted by my primary VHS project and forgot about the Betas. I recently went back to transferring the Betas, but after firing up the SL-HF500 it got thru only three tapes before the transport loading arm froze solid (I had to disassemble the thing to remove the tape). The SL-HF500 weighs a ton, and I really didn't want to drag it around or ship it for repairs. When I checked eBay, all the BetaMax listings were either "as-is," "cut AC cord" and other nonsense, or priced out of this world with no warranty. So I ended up paying WAY more than I wanted to spend for a SuperBetaHiFi sold by a retired Sony tech who has the entire suite of alignment and diagnostic tools in his basement. I figured it was worth the upfront $$$ hit to get a professionally overhauled Beta that would plow thru my 100 remaining Beta tapes without dying on me.
There are some good deals on used BetaMaxes, and its true you can probably get a better price on Craigs List than eBay. Just be aware the "affordable" Betas didn't quite make it to the modern bulletproof VCR era like VHS did: the very last truly-modern Betas were all ultra-luxe megabuck collector models that rarely pop up cheaply. The normal midrange consumer Betas that are commonly available typically date back to 1988 or earlier: they are a bit prehistoric in construction with many little things that can go bad. You can pay $79 for one that seems to work perfectly, and a week later it will lock up because of a blown capacitor in the loading circuit or capstan control board. Most of these have sat collecting dust for a decade or more, so a few days after power is re-applied the circuits start to blow from the stress and problems arise (it doesn't help that many of the most popular Betas run very hot).
If you need a BetaMax today, shop carefully, and consider buying an overhauled unit directly from a tech. Repairing a "bargain" that breaks can be difficult or costly. Unlike VHS, there are no Betas you can easily find for $15 mint at a thrift shop that will work flawlessly for the next ten years. Good used VHS vcrs are plentiful, durable, yet disposable and easily replaced. But Beta is an investment.