If your only pot is 16qt and you plan on doing biab, I'd say your next purchase should probably be a larger kettle, unless you prefer doing small batches. A 16qt stock pot with BIAB will be challenging to do a batch larger than 2 or 3 gallons. I'd suggest a 10 gallon kettle, though that's a tough find at $25. Aluminum will be cheaper than stainless, so that's the direction I went for the sake of cost back when I wasn't sure if I'd stick with this hobby.

I got this kettle shipped for $30.53. I lucked out by finding one that someone had returned (slightly dented) that amazon was trying to recoup something for. Even came with a lid, which I don't think that listing does normally.