You can get the 6qt sterilite tubs at Walmart for maybe $4 or so... forget the exact price, but they're very cheap. I use them for everything... weighing, bathing, temporary snake holders, rat thawing tubs...
Oops guess I missed the fact that you were asking about scales!
Once again Walmart sells a digital gram scale for $30. I got one on reptilebasics.com for a bit more but it works well.