I'd really like to get a search engine working within my website as I'm beginning to build up quite a large database of photos and it'd be useful for clients to be able to search for keywords within my site to find the photos they want.

I had a look around google but most of them are packages you pay for - is that the best way to do it or can you build from scratch (if so is that the long way round it?)

I build my sites using PHP and CSS.

Any information would be great thank you