DIY INVITES (long) sorry in advance

i ordered a mock kit from Card and stock.com.
now i am have a design sketched out but here is where i am stumped..

where should i buy the inner content...
1. Invitation
2. resonse card and envelopes

Do the kits at michaels or ac more include this.

Do you still do inner and outer envelopes with diY pocket folds.

Has anybody got an estimate on how much postage it is to send out Pocket folds? sorry for all the questions just trying to determine if i am better regarding finances making it your self or ordering them. of course if i order them im not going to order pocket folds. Open to all suggestions. Really looking to design a pocket fold fairy tale invite. Amy i crazy?

I ordered unassembled paneled invites from mygatsby.com. They also have all the components for the pocketfolds, you can order what you need. I thought the price was reasonable and you can edit, change spacing, font, letter size, and see what it will look like before you purchase.

PS The paper is a thick cardstock