Anyone know a good hotel near the beach in the Pisa area around £50 a night?

Answer 1

In the Pisa area the closest seaside resorts are mainly 2 :
Marina di Pisa and Tirrenia.

Here is a link for Marina di Pisa
http://en.venere.com/residences_pisa/marina_di_pisa/residence_boboba.html?action=user_rating&tf=user_rating.php&lg=en

the hotel here below is in Tirrenia and has special rates from Jan.29 till March 30.(starting from € 29 x night)
http://www.expedia.co.uk/pub/agent.dll?qscr=dspv&itid=&itdx=&itty=&from=f&shtl=1

however if you go back to the home page of both above web sites you can find other options.