You can never be too rich, too thin, or have enough clamps.
I don’t know about the first two, the last is for darn sure. So any time you have the opportunity to pick up more clamps, do so.
Look for them at your local home center – sometimes “old models” are discounted, or put on clearance. Trust me, clamps don’t have an expiration date or go out of style, so buy them on the cheap when you can.
Also try discount hardware stores. Yes, there is a difference in quality, but you’ll do fine for the most part with what’s there. I would, however, stay away from some of the bar clamp/spreaders at the discount places as they seem to be a little lacking in holding power. I’ve also found that you can pick up toggle clamps for a lot less than at premium woodworking stores. And spring clamps are a GREAT deal at the discount stores. The springs are quite as tight, but they do a decent job.
Go for a wide variety too, but be sure to pick up several of each size you choose. If you build a lot of large projects (benches for example), go for the largest bar clamps you can get (48″+) if you don’t use pipe clamps. I laminate a lot of boards for projects (making 1x into 2x or 3x), so I keep a lot of 4-inch F clamps and 6-inch bar clamps on hand.
And, with all these clamps around, you’ll have an excuse for building another project – a Mobile Clamp Stand!