birthday personalized invitations?

Looking to make birthday invitations with cute pictures. I found all on ebay only I want to know what software I need (and perhaps what it would cost) to create them. I think they are so cute and I want to invite some nice birthday calls and other events but do not want to buy want to create for myself. Here are some examples of what I'm trying to create examples are: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEBTOX:IT&item=110226822277&_trksid=p3984.cTODAY.m238.lVI and http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEBTOX:IT&item=170139838583&_trksid=p3984.cTODAY.m238.lVI and http://cgi.ebay.com/25-4x6-Hannah - Montana-Photo-Birthday-Party-Invitations_W0QQitemZ350035501662QQihZ022QQcategoryZ47113QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Hello, recently I have to create my own models and, like the ones shown here. I also sold on eBay and now my own website where they sell. The programs I use are Adobe Photoshop and Adobe Illustrator. Mostly Photoshop. It has a sort of learning curve, but if you can put it on when learning can create almost anything. Paint Shop Pro is also a good cheaper alternative. You can see my work on my site http://www.generalprints.com