This is a great idea though people that write product reviews will definitely be expecting something in return and since your website is new i will advise you to let the reviewers/writers understand whether they are writing for free, tips or postponed payment.
Yes I am paying for the articles. I will make specific arrangements when people contact me but generally I will break it up into small jobs and pay when it is completed. I can pay in Bitcoin or Paypal or some combination thereof.