Open source/ paid comparison website development

Hi,
I’m looking into developing a standalone price/product comparison website similiar to kaonsoftware.
Could someone suggest what is the best possible option for this?
I’ve read some post and review on www.kaonsoftwares.com/price-comparison-script.html and few others.
The review for kaonsoftware does not look so good so please suggest.

Thanks

See original post by losgrandes.yogi