15k isn't what I would consider cheap. Especially for the DIY type willing to fab things on their own.
I would start with a CHEAP vehicle. It's better to buy something as cheap as possible and replace everything than buy much more expensive and STILL need to replace everything or have parts with much more use if not replaced.
$1000 Bronco.
Rebuilt E40D $800 (by my brother in law-Ford tech)
$2,00 Rebuilt 302, including new water pmp, alt, starter
$450 Rebuilt rear 8.8 w/used aussie locker, free open carrier, forum sourced install kit, and used 4.56 gears. including H/D diff cover and fluids (do the work myself)
$550-600 Rebuilt front Dana 44 TTB with Dana 50 stub shaft (used-forum sourced) spicer joints, timken bearings mile marker premium hubs, 4.56's (used-forum sourced) forum sourced install kit and open 3.92 and up carrier.
$400 Rebuilt steering-rebuilt box, F350 2WD crew cab linkage, all new tie rod ends
$500 forum sourced and like new 35X12.5X18's with 18x9.5 wheels. Hankook MTO3's
$100 Trim fenders and tube/flat flares like on jeeps.
$300 Rear bumper with tire carrier, high lift and mount, built in ladder, DANA 44 spindle and hub for hinge, jerry can mounts with seperate swing out....
$350 custom front winch mount and shackles using stock bumper including harbor freight winch.
$100 Roof rack. Donated steel from atv crate, and sourced brackets.
This adds up to a grand total of
$6,550
This is my plan, and things that I have sourced already, or know that I can (for instance already discussed the trans rebuild with my brother in law)
On top of that price I would add some nice stock-ish height Deaver springs, front replacements from Napa, and some non reservoir Bilstein 7100's.
Maybe another $700
For my use I would add a roof top tent, on board shower system, and a fridge....
EASILY well below the 15k limit for a basically NEW vehicle.