I've been thinking of a cheap but cute favor for a fall wedding. I started to think about a custom mulling spice mix in some cute packaging. I didn't think of a good, sealed package until I was in the lab working with some bacterial cultures (I'm a scientist) and looked at some 15ml centrifuge tubes. They're sealed, sterile, have orange lids, an easily labeled surface, and I can get them for dirt cheap.
Is this too weird?

Re: Test tubes?
I think it is cute. I would love that!
I think it's a great idea. It reflects who you are and it's unique!!
Personally, I think that something like that looks better than the kind you actually use in lab (with the blue or orange plastic top) because they're a little more old-fashioned and IMO just look more attractive. I work in a lab with the orange top conicals every day, and I would be a little weirded out if I saw them with food in them because I would wonder if they came straight out of your lab and had thus been exposed to anything undesirable. Someone brought eggnog in the 50-mL conicals to our Christmas party last year, and no one would touch them.
They're sitting in a closet right now, and they were so cheap I would only charge for shipping - I think I can get them in one of those flat rate boxes for less than $6.
They were running a sale (30% off, maybe?), I'm not sure if that's a normal thing or not for them. I can let you know how many we have left and maybe you can just order more of the same to supplement? I also found some other sites that were selling them, which came up in my e-mail search:
www.testtubesonline.com
www.carolina.com
Maybe you could check those out, as well? We were consideirng using Erlenmeyers to hold our table numbers initially, and carolina.com had them for the lowest price at the time, I believe.
My Planning Bio - Update 8/5/12
I'm all for utility and function, but even I can't think of what I'd do with a sterile test tube.