Took a reciprocating saw to the stock to slice through stock and the bolt. Came off real easy, then.
The aftermarket folding stock (with pistol grip) is okay, but the forearm can catch on the stock if you leave it folded.
The best deal on the Mossberg 500a sub-model 50120 was from my local Walmart at $209 last year.
It came with wood stock and forearm. I wanted to make a handy home-defense gun out of it, and ordered a kit from Cheaper Than Dirt. The stock fit well, but the forearm was designed for the 500 defense pumps, not the sporting versions. So, I called Mossberg and ordered a new stock and forearm (I think it was the 56436 sub-model, but the tech can help you) for about $60 plus shipping.
Mossberg also has a pistol grip for the 500a for about $15 or so.
So, you could have a gun with several looks (wood w/18.5" or 28" barrel, black synthetic w/18.5" or 28" barrel, black w/folding stock or pistol grip w/18.5" barrel) for about $400. You can't buy two shotguns for that amount. Barrel changes are quick (less than a minute), stocks change in less than 5 minutes and the forearm takes about 10-15 minutes (some disassembly of the gun is required).
Now, as to must-haves: many folks here talk of a shotgun (12-guage); a varmint gun (small caliber like .22LR - Ruger 10/22 is good); a more powerful rifle for hunting (you can go cheap with a Mosin-Nagant), check you local hunting regs for minimum/maximum caliber, and magazine capacity; and a handgun for carry purposes. Find what works for you.
I'd recommend taking your daughter to a range that rents guns - you didn't specify type (rifle/handgun), so I'm going to assume rifle. Remington currently has a recall on the .17 caliber version of their 597 (I traded my .22LR 597 on a Ruger 10/22). I got the Ruger through Gallery of Guns using their Gun Genie (they show local FFL dealers and total cost), you have to order on line to get the best deal. My 10/22 took three days to get to the dealer and cost me about $245 (less with what the dealer gave me in trade for the Remington). You can likely get the most basic version for about $220.
1/2 socket = 1/2” socket.