Unless i misunderstand your question but i dont think you need an escrow script for this operations on your website, all you need is a dedicated btc address called interceptor that will not all the seller to receive the funds instantly unless confirmed satisfied by the buyer.
Some bitcoin api can do this job just check
https://blockchain.info/apisomething like that i need<<
1)buyer send fund to marketplace
2) marketplace confirm fund received and alert seller
3) seller send items to buyer
4) buyer confirm that he receive his product
5)marketplace release fund to seller