Try NailOrder - they do 'pre designed express nails', which are on their site (or pages 22 and 23 of the paper catalogue/pdf).
They say they originally planned them as weekenders, but they last up to 2 weeks or so, so would work for a holiday, too, maybe, and soak off in acetone.
They have over 20 designs in varying lengths, and cost £6.95 pre VAT for a box of 24 tips. They recommend you charge £15-20 per set, although I guess that would depend what local prices for a full set were.
I'm pretty sure there are other suppliers that will stock them too.
I was thinking of offering these as I know none of the local salons stock them currently, but I wasn't sure if I could afford to keep enough designs in stock at one time. There's the question of initial outlay - what if you pick, say, 6 designs to stock, some are really popular, and you never shift the others..?
By the way, I'm not breaking any forum rules by mentioning suppliers or costs, am I? I hope I'm just being helpful, but I thought I remembered seeing once someone saying 'PM me with costs as I know we're not allowed to discuss prices'. Am I being bad here?:o