I train in and have fought with this mouth guard:
http://www.titlemma.com/sf_32/pg_1/c_4/p_SDMP+2+BL.aspx
I custom made mouth piece can be expensive but is your best bet.
If you want a good, cheap compression shirt or rash guard go to Wal Mart and buy the Under Armour knock offs for about 12 bucks.
"The hero and the coward both feel the same thing, but the hero projects his fear onto his opponent while the coward runs. 'Fear'. It's the same thing, but it's what you do with it that matters". -Cus D'Amato