This will be my 2nd year growing citrus in ground here in 7b-- so 8b should be a lot easier! Some of the citrus I am growing is a little more cold sensitive so it is sheltered on the south of my house against the brick wall and fireplace. Just fruits and exotics I've purchased from before but unless you are in FL you'll need to drive down for a pickup. Mckenzie farms is also good and the owner is a great person to chat with-- I think they may ship(?) but their listings online are seriously lacking. The other site that was mentioned, I've not looked at previously.
I've purchased a number of citrus from
one green world and they are great as well.
I would suggest some reading
Cold Hardy Citrus for the South East. It is a little painful due to formatting (scanned from hard copy) but it is the only one I've been able to find. It will break down a number of varieties that can be grown. The list given there is pretty surprising at least to me and I'll be expanding out greatly with them.
California's Citrus Clonal Protection Program seems to also offer good grafting material. I've not purchased from them yet however.
Fruitwood Nursery has also started offering cuttings and I have a lot from them under light/heat now trying to get them to root.
Good luck-- cold hardy citrus can be an addicting hobby!