hi furry. i'm new to the forum too and just like you i lurked here *forever*. never EVER would've signed up if the information hadn't been SO good and the people so friendly and NICE.
anyway, i haven't posted about this stuff yet bc i'm still trying it out...but it might be of help to you in the light department for not very much $$$. i discovered this stuff called Reflectix at home depot. it's basically really hardy regular old bubble wrap with radiant barrier grade reflective "foil" on one or both sides of the bubble wrap (obviously the one sided stuff is a little cheaper than the two-sided but not by much, imo). anyway i've never seen a grow tent, only pictures, but what i bought looks exactly the same as the inside of the pics of grow tents but a LOT brighter. you buy it by the roll and it's pretty cheap per foot. it's really really flexible too so it makes it really easy to work with and to move around if you need to. for example, i'm using it to make a little room within a room right now during germination stage. i hope maybe that stuff might be affordable enough that it might be of some help to you.