You guys were right

Boilovers sure are messy.

I just got my indoor brewing priviledges revoked by my wife, which sucks because winter is gonna be cold out.

On the up side, she is pretty awesome, and she told me that she is going to make me buy a bigger pot so I don't make a mess again. However, she says that I can only buy one more pot "ever." My apparent budget is ~$350. That said, if you were given that ultimatum which pot would you get?

350 would buy you a keggle (assuming CL price), banjo burner, valves, MLT, and some other cool stuff

Something like this?
http://www.austinhomebrew.com/product_info.php?cPath=178_33_463&products_id=11291

$350 is a lot of money for an indoor pot. I've got a 15gal pot and while it just fits under the hood height wise, my indoor stove (propane) can't get a real good boil going with more than about 4gal in the pot. So, I pretty much have to do the boil outside (but can still use the stove for the mash/sparge water heating in my old 5gal pot).

So, if your indoor only, I'm not sure I would go bigger than an 8gal pot (and use the money saved on other goodies).

Well, you have to ask some questions first. Will you ever brew 10 gallon batches? If yes then you want keggle or 15 gallon brew pot, if not 10 gallons would work. Next do you want to spend the full $350 on a pot? If yes you generally can't go wrong with Blinchman, if no Polarware should work fine for less money. There is also a seller on Ebay selling SS pots with spigots out of China from time to time that is even less. I have one of his 9 gallons and considering the price I am mostly content with the quality. Really other than the welded spigot not extending past the inside wall of the pot (which means you can't attach a hop filter) it works pretty well.

I am actually no longer able to brew indoors thanks to the large sticky stinky mess, so am looking for outdoors, thanks for the advice.

You'll notice there is a huge price jump from 10 to 15 gallons, about triple. Unless you plan on doing 10 gallon AG batches, you'd be better off buying a 10 gallon pot and spend the rest on a burner, tanks, etc.

If you are going to have to brew outside I would suggest a keg.