We bought some stainless steel water bottles at Things Engraved the other day....They were on sale for $2.50 (from $10) and I asked for an additional discount since I was buying 26. She gave me an extra 10% off. I bought red ones for the girls and blue ones for the guys. They are nice quality too and have the little clip on the lid.
Also, wanted to mention that they have some really cute beach theme luggage tags there...I didn't buy any because I already made some, but wanted to let other brides know!