Hello and welcome to TBN.
One thing to consider when comparing prices is whether the dealer is quoting you the tractor with any options installed. Last month I just purchased a 2720 with the following equipment:
2720 with front and rear aux lights, independent mower lift, brush guards, and block heater
62D mower
200CX loader
54" front quickhitch blade
ballast box
i-match
3ph 2" receiver
My total price for this package was $21,738. Of that $21,738, $1100 was the front blade so if you subtract that off, you can get a good idea where you stand for your package. I should also note that the independent lift included in my package was a $700 option. That's why I mention asking the dealer if he included any options on the tractor at that price. All total my tractor had close to $1000 of added options. Your dealer may have added in those options as well and should be considered when you're comparing prices. All told, my package discount ended up at 17% off list but I had a trade-in. If you are buying out-right, you may be able to negotiate a slightly better deal. Also, JD's current incentive program gives you an additional $200 off if you buy two attachments with your tractor.
Yes, the 2520 and 2720 are the same with the exception of the engine. I had actually made the deal on a 2520, but did some additional reading here and another tractor site. My house sits on a hill so I have a couple steep inclines to mow and overall gradual slope to my land. The only real complaint you'll see about the 2000 series tractors is that they only have a 2-speed hydro. Any of the 2x20 tractors will do anything you need them to do in low. However, you'll see some complaints about gearing in high range when attempting anything other than transporting the tractor empty. I really didn't want to be limited to mowing or pushing snow to low range only. I wanted to have the power available to mow or push snow in high if I desired to do so. After reading several posts complaining that the 2520 did not have enough torque to mow on anything put pretty-much level ground while in high range, I decided it was worth the extra $1500 to step up to a 2720. I really would've liked to step up to a 3320 with its 3-range hydro but that was another $5000 jump with the equipment I wanted. I've only put a couple hours on my tractor pushing snow, but I can tell you it's just what I hoped it would be. I'm not saying the 2520 wouldn't have worked for me, however, with my 2720 I was able to pull my utility trailer full of wood up my driveway in high gear just fine. I haven't pushed any heavy snow with it yet, but from my experience with it so far, I doubt I'll have any issues pushing in high if I desire.
My advice is to consider your terrain and what you'd like to do with the tractor. If you plan to mow any kind of slope with a 2520, expect to be limited to doing that in low range. Max speed in low, per JD, is 4.5mph. That's a pretty good clip to mow at, especially if your lawn is rough. My land is a nicely established yard and I anticipate most of time I will still mow in low. However, I foresaw the situation where I'll be in a hurry or needing to get the mowing finished quickly (or the driveway plowed) where 4.5mph might seem too slow. It was worth an additional $1500 to get the additional 5hp, and more importantly the additional 11ft/lbs torque (51.3 for the 2520 and 63 for the 2720). When you look at it, you're getting a 20% bump in torque at a slightly lower rated rpm. Additionally, if you look at JD's specs, you also get a slightly better fuel consumption rate on the 2720.
Most will say buy the 2520 or if additional power is needed go to a 3000 series. To me, the jump in price to a 3000 series wasn't necessary, but I really wanted to insure I wouldn't regret buying a tractor that MIGHT let me down power-wise. If you're in a similar situation, then I would highly recommend the 2720.
John