Please excuse this dumb question - what is a thumb? I would love to get a backhoe - would you recommend getting that when I make the initial purchase if I decide to purchase new?
Backhoes may be tough to find if not bought new with the machine - the better ones have a sub-frame (to attach to the tractor in multiple places to avoid concentrating the forces) which is specific to a brand, and likely to a small range of models in that brand. There are generic 3ph backhoes but common wisdom says that they abuse the tractor they're attached to. They're all expensive, and people selling used backhoe attachments know how much they cost and unless they're in a big hurry to sell you'd think they're made of gold.
A backhoe will likely add 1/3 to the price of a new machine.
Think long and hard if you really need a backhoe, or if you can get by with renting one - my local town's rental place has Kubota B and L TLB's for rent, and you can rent many times for the price of a backhoe for your machine... and their backhoe is probably stronger than yours will be as well (the
B21/26 &
L35/
L39 are really heavy duty machines).
Before I had a tractor, I often made lists of things to do "next time I rent a backhoe", because a rental here is 4-hour minimum - from when you pick it up to when you drop it off, and that's 30 minutes each way plus a bit of time at the shop and a stop at the fuel station to refill their diesel. That 4 hour minumum ends up being a safer 2 hours of work, for the 4 hour rate (which is like 80% of the day rate), so economically I never wanted to rent for less than a day. You can get a LOT done in a day, so make sure you have a lot of digging lined up to make it worth it!
More often than not though, my list never got long enough for a rental because most of my digging jobs tend to be "I need this hole dug NOW", like "I broke a pipe mowing and need to redo a bunch of plumbing" and so out came the pick & shovel and my back hurt because I'm not going to go rent a backhoe for a little hole! (... yeah I was digging for 4 hours, I should've rented... but also, the rental yard only has a couple machines for rent and they're not always available!) The only times I ever rented a tractor/backhoe back then was when I had a dead horse to bury, not doing that by hand.
So when I started shopping for a tractor, I knew that the "stack up projects to rent a backhoe" just doesn't work for me, and I decided that adding $7000 to the price of my otherwise $23k tractor for a backhoe was worth it. And, it is - as far as my jobs go. Economically, I'd probably still be ahead if I rented for most of the digs I've done, but renting is kinda a hassle, too. I prefer being able to just fire up the tractor, drive over there and dig. Maybe dig more tomorrow, I'm not constrained to a rental schedule. Take off the backhoe and put a different implement on, no worries (20 minutes for the swap), I can swap again soon enough if I need.
But, it's still pretty expensive.
Oh, add the $1k welder bill I just recently paid because my backhoe subframe developed a crack. From the pictures I've seen on the net, it's a design/manufacturing defect, but I bought the tractor 7 years ago so no warranty on that at this point.
Still, I'd buy a backhoe with a new tractor again, but then I also do a lot of digging. For you, with a relatively tight budget, you may want to consider if sinking such a big chunk of that budget into an occasional-use piece that you
can rent makes sense. Assuming, of course, that there's a near-ish rental yard, and you can tow their tractor on their trailer; they may also deliver & pick up, which will add considerably to the price of the rental, but it's also pretty convenient because the clock is typically only ticking when you have the equipment (I did this a couple years ago with a 5k telehandler to put up some tall landscaping structures - (it was too big & heavy for my 1-ton truck to tow) 30 minutes of work for $475 including delivery, but it was soooo easyyy). If I didn't have lots of digging projects and a smaller budget, not getting a backhoe would be a no-brainer.
Oh, also. I mentioned previously the "stump bucket" attachment that can go on the loader? That can probably handle a lot of the smaller digging jobs you may otherwise want a backhoe for (removing shrubs or small trees, big rocks/small boulders).
Way cheaper than a backhoe, though a totally different tool... just may have enough overlap to be useful enough to put off a big backhoe bill.