Weddingbee boards

I'm an invitation designer, but I can't really give you proper advice because it sounds like your business would be much different.  As for me, I don't actually handle the printing and all the materials (primarily because I would also run into issues with limited space, etc., as I live in an apartment).  After speaking with many graphic designers and listening to their suggestions, I decided it would be best just to handle the design side and let my customers take care of their own printing.  Maybe in the future I'll actually assemble the invitations myself, but I'm not ready to run two separate businesses (because basically that's what it would be like). 

Good luck though!  I hope you get more replies from people with experience.  If it were me, I'd probably just be upfront with my clients and explain that the work is custom (or semi-custom at least) which means the turn-around time will be a little longer than usual.  If you give yourself, say, at least 3-4 weeks to finish each customer's order, would that be enough time to order the supplies and make them?