Setting up my own buisiness, need advice on software

Hi, i am currently in the proccess of setting up my own online buisiness and need a little help on what software i can use for what my site will be doing.

On my websiter i will be selling posters, photos, postcards etc. So what i need is an image gallery kind of thing with a shopping cart built into it so i can accept payments for them.

I know there are a lot out there but because i am only just setting up the buisiness i have a very small budget and the majority of that has gone on hosting, domains and the things i need to make the posters.

So what i wanted to know is, if any of you guys knew of any FREE or CHEAP scripts that did this kind of thing, just to put me on untill the buisiness has set off and earned enough money to buy a proffesional one.

If you need any more information, feel free to ask.

Thanks, mark.