Since you're already on bb.com, plenty of info there to help you reach your fitness goal, but here are some suggestions to help you find a good quality cage. First off, your work space seems tight, need to free up space to accommodate a regular size cage in there with your other equipments.
I suggests removing the benchpress (after you find a cage) to free up space where you can safely perform multiple exercises without the need for spotter. Selling the bench you can up your budget a little more to buy better equipments. If your budget for a rack and bench is fixed to 450, it's going to be a while to find anything quality, but the deals are out there. On a couple of occasions, I've seen used power cages for 200-300 on CL, so like I said be patience and keep scouring you local classifieds.
A quality cage should be made of 11 gauge steel and have a minimum weight capacity no less than 500-600# imo, the more weight it can support the better...even if you won't be flinging that much weight around yet, the extra strength ensures your safety and durability.
http://www.thebenchpress.com/shop/pr...d=113&cPath=25
For casual lifting, I suggests taking a look at the Powertec, it has all the good qualities of a heavyweight cage but compact enough to fit into the space you've got. They cost a little more than the Chinese made ones you see at D1ck's but you get what you pay here. If you can't find a used Powertec in your area, its specs are good standards what to look for, find another cage with similar specs and you're good.
https://losangeles.craigslist.org/sf...607192861.html
Here's an example of the kind of deals for the powertec. The asking price is 850 but that includes weights, FID bench, and some attachments. This package will likely end up selling for 500-600 because not too many are out to build home gyms when they can join public gyms for $10 a month.