Vistaprint for sure! I spent $66 on 90 invites and 140 return address stickers during one of their 50% off sales. I also think based off my emails they’re having a big sale for Black Friday so if you’re looking to order soon I’d do it then!
Vistaprint. best pricing for invites. you can upload your own design. or they have TONS of awesome designs. and for a small fee they will even design for you.
you can get them to send you a free paper sample so you can see/feel it in person.
and wait till they have a sale on them. which they do frequently.
zazzle is another awesome site. but vistaprint is more cost effective than them.