Hello! I'm offer you to make website in Ruby On Rails platform, which is used by twitter, groupon, etc. - [login to view URL]
It's not only good looking, but allow to make websites several times faster then in PHP, thus you will pay less for job.
For the back-end I suppose to use MySQL and pure Ruby - it is modern, very fast program language, suitable for API, it could handle amazing quantity of requests, I've made recently PPC system (pay per click)on ruby that can handle up to 7000-10000 requests per second. PHP would failed at 2000-3000. Also, it is also faster to develop and result code is higher quality.
Also, I'm offer 40% discount of regular price (already included in cost) - for reasons why do you get this promotion please click on my nick.