Considering a used R13 purchase, or buying my rental E11 or a frankenclarinet...help please!

I'm returning to clarinet after 20+ years. I played on an R13 back in middle school/high school and I was considering a professional career until band conflicting with AP classes forced my hands to quit. I sold the R13 (which I had purchased brand new in the late 90s -- it might have been a green line, but I don't remember for sure) and that was that. I started renting a clarinet from a local shop earlier this year (an E11), and it's fine. There are a few things that need to be adjusted/pads replaced, but overall it seems good enough, and muscle memory kicked in. I'm probably as good as I was in 7th grade after playing once per week for a few months this time around.

I don't want to keep renting forever because it's throwing money away. I'm enjoying it, and would like to buy one. If I want to buy my rental, it will be about $1600 (and the money I've spent renting it will count toward the purchase price). If I decide to buy my rental, then I can keep renting it for a bit to make sure I like it. But also, from Googling it seems like that's an insane price for an E11 and is way overpriced.

The rental place is replacing the pads and gave me a loaner in the meantime, which is a Buffet frankenclarinet. (Per Google search/Gemini's automatic AI, the lower joint might be from an R13 and the upper joint is probably an E11 or 12. They have mismatched serial numbers so there's at least 2 different instrument parts in the case. The barrel and bell don't have serial numbers but do have remnants of a Buffet logo). Because it's old, and there is a chip in the lower joint right where it attaches to the bell, they said they'd give me a helluva deal -- like sub $500 for it. It plays fine. Better than the original E11 that they're fixing.

There's a woodwind store near me and they have a couple clarinets in their supply. I am currently testing an R13 on a trial, which I have until next week. They have another person who is interested in it, but I have first dibs. They're asking about $2100 for the R13. Allegedly it was owned by a professional clarinetist, per the sales guy at the shop, and he says it was well-maintained. This list makes it look like it was 1987, assuming that long list is all R13 serial numbers. When I googled it, Google's automatic AI said it's 1997 or 1977 or 1985 (Gemini is worthless and can't make up its mind lol).

The sales guy is encouraging me to go the R13 route, and so far it's been great to play on and feels like my old one, but I'm also biased b/c it was my old instrument type lol. It's hard to swallow paying that much though, because I'm pretty sure my brand new R13 back in the day was like $2000 and I sold it for $1500 in 2003. An older instrument that's more expensive is hard to justify.

I also can't really hear or feel much of a difference between the R13 and the E11 and the frankenclarinet, though that's probably because I'm not that good yet. The sales guy was talking about "flexibility" and "brightness" and stuff as I was testing different models, but I don't really know what that means (I'm not sure I really understood it at my peak playing ability when I was first chair of our audition-based wind ensemble, either, tbh).

Realistically, I'm going to play maybe once per week at most (probably less, if current habits are anything to go on). I toyed with the idea of joining a community band, but I don't really have time for that. Maybe I'd volunteer to play in the pit for a local theater at some point if I got good enough. But really it's just me playing along to random youtube video clarinet music mixes on my couch for an hour until my embouchure gives out and my face hurts and then doing that again a few weeks later.

I want something that I'll enjoy picking up and not get frustrated with, and that will make me want to play more. I have noticed considerable improvement each time I play, so I think if I did actually practice a few times per week I would be pretty good within the year.

TL;DR: What would you do? Is it really worth an extra $500 (over the E11) or an extra $1500+ (over the Frankenclarinet) for the R13? (I have the money, so it's not going to bankrupt me. It's more of a psychological thing -- I'm also hesitant to spend more than 2tx my mortgage payment on a clarinet for a hobby, because that seems insane.)

Is an R13 for around $2100 that is potentially 30-40 years old a good deal? (There's not a warranty, but it does look to be in good shape). Is there anything I should specifically look for on the instrument to help confirm quality?

FWIW, the local shop has great reviews online and is reputable. Thanks for any insight! I just don't want to regret my decision, whatever it is.