If you hurry, www.rareplants.eu has a huge selection. This year the bonus seed pack they send is Aeonium canariense (50 seeds!). Their seeds are very good, and full of unusual varieties. I just placed another order from them for 3 varieties of guave. A lot of my moraea and gladiolus seeds came from them. There are also articles on how to start the seeds.

Seed of these is very fine, so don't try sowing it in a windy spot!. Seriously, the best way to sow it is to use well drained compost, put a layer of grit on top then sow the seeds on that. Water by putting the pot in a soaking tray and allowing it to take up the water rather than overhead watering, unless you can find a fine, gentle water sprayer.
If you get really into Sedums then try joining the Sedum Society and getting seeds from their seed list.

Thanks Wylie, I think that site might be a bit too exotic, nice to look at though☺
OB, thanks! Just the sort of info I need to get started. Having looked online I can probably get 250 mixed seeds of each for a tenner Incl. P&P. Then I can keep the best ones & sell the rest to raise some pennies for the garden group.
What sort of surface area would I need to sow 250 seeds if I made a big tray? Or would I be better getting a load of those cheap plastic module sheets?

Sorry did not see this sooner.
I use half depth pots of about 6 ins diameter. You would need 5 to 8 of them for that many seeds.

Thanks OB!