Ooh buddy80 that's a great link, sweet peas are very cheap and flower continuously, they also do better if you pick them so are probably the best out of the bunch. Gypsophila is also a good one as it will benefit from the cutting.
I will tell you a secret from my business. I buy my plants and bulbs at the local farmers auction. This year for Christmas pressies I bought a huge bag of bulbs, 150 at £15.00 of tete a tete daffodil's and some pots from the range and am planting them up for Christmas. Next year I will probably sell them to customers too.
For your own garden go to the auction after the nursery so you know the going retail rate, super easy to bid at auction and things like trees are much cheaper think £5 instead of £30. Massive bags of bulbs far far cheaper than the nursery.
Just don't bid against me !