Check out the posts here Chinese Diggers - there;s a few of them - good reading.
I have a backhoe on my NH TC33DA and other posters are correct: huge PITA to hook up every time for small jobs and robs you of the rear implement whenever it is mounted. IMO, very tough on the tractor without the subframe. The weight really stresses the joint between the front and rear of the tractor. Sooooo, I opened my wallet and spent $7K USD for a new chinese mini-excavator with enclosed cab. I had a hard time initially with the idea that my excavator would run on a "lawn mower" engine, but all the engine does is run a hydraulic pump so I got over that. Works like a charm, built very sturdy. If I could do it again I think I would skip the enclosed cab. Makes maintenance harder unless you are small and have small hands. First oil/hydraulic change took 4 hours because I didn't have a funnel with a long bendable spout to snake around the build barriers to easier maintenance. Got it done with lessons learned. Easier after the first time. Not meant to pull huge stumps or boulders, but I love it to fire up and do a small job. Sneaks around buildings and in the woods easily with the small footprint. I use it way more than I thought I would just because it's so convenient to turn the key and work. All that said, be careful if you buy one. They are pretty powerful for their size and I can see someone without a lot of experience running this type of machine getting into trouble easily. Go out and dig some holes and pull some stones in a safe area to get the feel of the limits of the machine. On the plus side, parts and accessories (thumbs, buckets, motors) are "off the shelf" and most can be ordered on Amazon or EBayJust my two cents worth.Not quite a direct answer to your question, but in Eastern Ontario I sold my BH860 backhoe on consignment at the dealer for C$7,900 last summer. That's with subframe, larger model than whatever you're getting (mine was on a Branson 4225H), 4 years old, well-used with some dings. I bought it new for C$9500 in 2019. Given yours is smaller (K680?), and this annoying detail called inflation, the price you're being quoted is not unreasonable.
Yeah, these Chinese mini-excavators, especially with good quality motors, are worth thinking about. We sold our backhoe since we got a Kubota KX-040 and having a dedicated mini-ex is the bees knees. Now the KX-040 is not a Chinese off-brand, of course, and it's a much larger machine (4 ton, so bucket breakout force about 2x our old BH860 and 4x a K680 ). It cost quite a bit more but also holds value pretty well. I'm still not wholly sold on the Chinese off-brands as good alternatives to a brand-name mini-ex, but definitely worth thinking hard about as an alternative to a backhoe attachment. Especially if you're handy and have access to a shop so you can maintain it, do mods, and fix problems down the road yourself.