Please note that there are WAY more vendors in SL than what's listed here! These are just a few that our community is experienced with and know. Don't let our limited knowledge constrain your search!
These are links to merchants that sell complete furry avatars. Everything you need will be in the box when you purchase it.
These are vendors that sell "mod kits," meaning that they sell kits to modify an AV you bought from someone else. You'll have to have the base AV first before you can use a mod kit.
Head to a sandbox. Our building garden works well for this. Drag the box you get from the vendor on the ground, right click on it and hit "open." Then hit "Add to Inventory".
This is still being built! This is not a complete list! We're still working on it!!
If you're looking for ideas, check out the SLARF website. It's full of awesome photos!