I always make my own, it's nice when you can match them in some way to the front of the card. If I have a nice design on the front I will use it on the inside and reduce the opacity so it looks like a background image.

The problem is when the cards are larger than 6x6 and I have to print them on an A4 printer. But I've worked a way round that by printing them on A3 paper cut down to A4 in width and if I print the insert upside down it works out perfectly. Of course, it would be easier to buy an A3 printer but the last one I bought was a Brother and it was a nightmare to feed the A3 paper in.

If anyone has come up with a better way of printing them do let me know. I used to print them in two halves but if you don't get the join just right and by that I mean completely invisible, then it messes up the whole card.