Agreed with @Millgate, be very very careful to check that what they are quoting is correct and keep a paper trail as it's pretty easy for suppliers to quote the wrong part either accidentally or deliberately. Make sure the quote shows the Microsoft part codes and check those codes against the other quotes you receive, if codes vary then investigate.
It's worth checking that the reseller is actually authorised to sell Educational Licences, a list can be found here - Microsoft UK Education - Software Licensing - Education Licence Resellers

