C.F.
Don't know where you could get a cheap trundle, but if Haverty's (overpriced furniture) has them for $99, then try Kane's or even the RTG regular or outlet. My friend bought a nice bunkbed from Sam's Club or Target (can't remember which). They can either be stacked or left as two seperate beds.
Definitely watch Craigslist or the flyer for baby deals, since you need baby items, as well. I also recommend children's consignments for clothing (which they outgrow superfast) and even cribs, highchairs, strollers, or swings. The best one I've been to is Once Upon a Child, one is in Brandon and the other near Lutz. Also Amazon.com often has free shipping for on orders over $25. You can read the product reviews, compare items and prices, and never have to waste the gas. :)