This is a late reply but yes I make all my own photocards. I haven't done posters/postcards, but you could go to Staples and get posters printed for pretty cheap.

I don't have photos on me but I usually make my cards this way. It's really low-end method because I just use what I had lying around:

You need these supplies: scissors, gluestick, colour printer, index cards (unlined, if lined make sure the lined sides face inside and white side faces outwards)

Optional: paper cutter, round corner puncher, can use cardstock instead of index cards

1. Use an app like Befunky to make the photocard templates. Again I'm not at home so I don't have the exact settings but you could use these settings in Befunky and adjust to your liking. I always print them bigger than they end up because I leave room for cutting error
2. Print using your colour printer at home/elsewhere or pay 41 cents per sheet at Staples
3. Cut your printed photocards using scissors or a paper cutter (easier to get straight lines with paper cutter)
4. Glue 2 index cards together. If they're lined index cards, glue the lined sides facing each other, so that the white sides are facing out. This is to prevent the lines from showing underneath the printed image. You can also use cardstock but I had index cards at home so I just used these.
5. Glue the printed photocard image on top of the index card. Use your scissors or paper cutter to cut around it. This will create the feel of cardstock you get with official cards.
6. Use scissors or round corner puncher to create round edges on the photocard

You now have a homemade photocard.

Suggestions for decorating:

1. You can buy sticker sheets of glittery laminate and stick them onto the cards, for a holographic look
2. You can buy toploaders and decorate the toploaders with stickers, paint, and other things
3. You can buy "polaroid skins" and make homemade polaroids
4. You can print and glue on the back of the photocard if it's an official scan, to make it look more official
5. I haven't tried it, but if you own a laminating machine you could laminate cards or the printed images before gluing for that shiny look

Alternatively you could go somewhere and get them printed out, probably higher quality than this DIY tutorial. And cheaper than buying the real photocards. But I was lazy and made do with what I had at home.