Repairs are not expensive if you do it yourself. If you are unable to do it yourself then it’s obviously considerably expensive.
I would look for a deal on a pair of M3Ds then put a light kit on it and you pretty much have tables nicer looking that function the same as MK5s for cheaper. A very good price to pay for a pair of M3Ds would be $500. You may have to pay 600-700 which is still a good deal relatively. Expect to pay closer to 800 for a deal on a pair of MK5s. Forget M5gs, they are ugly and overpriced.
I have a few posts about what to look for you can search through them or I’ll find them.
as for a recommeded model every model will do great. as i understand most people use MK2s or MK5Gs but due to their popularity they also sport the biggest price tags (up to 900€ a piece for a new one where i live). your best bet is to for a good used pair of either the MK2s or one of the the less popular models.
I have MK2s, and I’ll say you’re better off with the M3Ds to the point that I’d pay an extra $100 for a pair. $600 for a pair of MK2s is reasonable to good around where I am; I got mine for $500 for the pair but I did have to replace an RCA and a power cord for that. For calibrating the tonearm etc. look on youtube for videos by ellaskins and viperfrank - they have pretty good tutorials for that type of thing. For needles, especially if you’re just using timecode, get some Shure M44-7 s or M44G s. They don’t skip, have decent quality if you actually do play vinyl, and are fairly inexpensive as far as carts go. Slipmats… I have Dr Suzuki Mix Edition mats and some Butter Rugs. I like the Suzukis for getting the vinyl back to platter speed quickly, but they’re almost a bit too sticky for my taste. The butter rugs are nice, but a bit insubstantial and the vinyl wobbles a bit with just them. I’m currently using both slipmats (a bit unorthodox) which I find is actually a pretty nice happy median. I’ve also heard good things about Table Cloths.
Repair wise you can find pretty much any part online and it’s usually pretty easy to do yourself as long as you can solder. Just watch out - the platter is about $100 to replace, the tonearm is about $50, and the FEET cost a total of $50. The small repairs can add up. That said, replacing an RCA cable could cost you about $10 to do and you could knock $50-100 off the price for it.
Oh, a little protip for you too: search craigslist for technics 1210 too; you can get a replacement power cord for $20 or so off of amazon and since not many people search for 1210s, you can sometimes get a pretty damn good deal. My 1210 was missing a counterweight and I got the guy to give it to me for $200 (from $250 originally). So at $250 after the counterweight and power cable were replaced I was pretty happy with it.