The Pro Studio Solutions Scrim Kits are easy to assemble, breaks down quickly, and is lightweight. The included telescoping boom arm (available in some kits) is very good quality and weighted as a good counterbalance. Starting at around $119 (for the smallest one), I think it's a good buy and something you'll end up using for years. You can find the ProStudio Kits available via Amazon (here).
Hunter writes in and shares one of his recent budget purchases. It's a collapsible 43" Light Disc with 5 Different color reflectors including white, silver, and gold. Perfect lightweight solution If you're looking for a simple, fast, effective way to throw some fill light onto a subject. It can also be used as a bounce when using flash photography, a small scrim, or light diffuser with continuous lighting kits. Follow the link to find some even cheaper deals if you're looking for something a bit smaller than 43". [Thanks Hunter]