Around here in MN we were seeing 07-08s in the 20-25K range with mileage in the 80-105K range. Granted we were more focused on the LTZ. We wanted the Nav not so much for the Nav but for the full size screen for the backup camera and DVD for the kids. We have a camper so the ease of hooking up a trailer is worth it. Many times my wife will hitch up the trailer and I meet them at the campground. Sure you don't have to get a LTZ to get these items but they were more common in them. In the end we ended up with a 2011 Denali with 96K that was equipped like I would have ordered it for $27. Every option but 22 rims and power running boards. Though Denalis have a pretty short list of options.
Some issues to watch for. A buddy of mine had a 07 Z71 Tahoe and had the oil consumption issues. This will be hard to spot in a test drive but he was burning 1 qt per 1000 miles. I have seen some talk of new valve covers which address this. I thought he said they replaced the heads in his but he isn't really technical when it comes to cars so he wasn't sure. I want to say that it was around 2010 that they made some changes to address this.
In the 6.2 found in the Denali and Escalade (also some Tahoes 09 I think) there were some issues with cam bearings. 09 addressed that also adding flex fuel compatibility. 10 they added active fuel management. While the Denali and Escalade will get get worse mileage because the bigger engine and AWD, it isn't much. 1MPG or so if you take it easy but that isn't easy. I have noticed that it gets better mileage than the 03 Avalanche that it replaced.
The dash cracking is pretty common as you noted. Mine isn't cracked at all. Another common issue is the door handle on the inside of the truck. The chrome plating (wrap) peels off leaving the edges sharp. A Tahoe Z71 I drove was like this. They are not too expensive to replace. I want to say I looked them up and they were $15-20. A common issue with used vehicles is keys. My Denali came with 1 key and 1 fob. I negotiated a second fob and key in the sale. I asked about additional keys but they said the fobs were really expensive. They also would only let me have 2 keys as part of the deal. I went to another dealer closer one day and had 2 more keys cut ($30 a pop). In 2007-2010 you can program fobs and keys yourself. You can get them cheaper on ebay or other places. In 2011+ you have to go to a dealer or someone with a Tech2 programmer to add fobs. Keys can be programmed though in all of them.
The 15K budget may make it hard. You can probably find them out there in that range but it will take more time. Of course if you are fine with the lesser equipped LT range then that will make it a bit easier.
Some issues to watch for. A buddy of mine had a 07 Z71 Tahoe and had the oil consumption issues. This will be hard to spot in a test drive but he was burning 1 qt per 1000 miles. I have seen some talk of new valve covers which address this. I thought he said they replaced the heads in his but he isn't really technical when it comes to cars so he wasn't sure. I want to say that it was around 2010 that they made some changes to address this.
In the 6.2 found in the Denali and Escalade (also some Tahoes 09 I think) there were some issues with cam bearings. 09 addressed that also adding flex fuel compatibility. 10 they added active fuel management. While the Denali and Escalade will get get worse mileage because the bigger engine and AWD, it isn't much. 1MPG or so if you take it easy but that isn't easy. I have noticed that it gets better mileage than the 03 Avalanche that it replaced.
The dash cracking is pretty common as you noted. Mine isn't cracked at all. Another common issue is the door handle on the inside of the truck. The chrome plating (wrap) peels off leaving the edges sharp. A Tahoe Z71 I drove was like this. They are not too expensive to replace. I want to say I looked them up and they were $15-20. A common issue with used vehicles is keys. My Denali came with 1 key and 1 fob. I negotiated a second fob and key in the sale. I asked about additional keys but they said the fobs were really expensive. They also would only let me have 2 keys as part of the deal. I went to another dealer closer one day and had 2 more keys cut ($30 a pop). In 2007-2010 you can program fobs and keys yourself. You can get them cheaper on ebay or other places. In 2011+ you have to go to a dealer or someone with a Tech2 programmer to add fobs. Keys can be programmed though in all of them.
The 15K budget may make it hard. You can probably find them out there in that range but it will take more time. Of course if you are fine with the lesser equipped LT range then that will make it a bit easier.
