98 Altima check engine soon light - evap valve?

I researched this thread and found a post that described exactly what seem to be wrong with my car.

When filling up with gas, the gas pump keeps shutting off. Seems to be a pressure issue possibly related to the evaporative fuel canister. Someone posted that they changed their "evaporative canister valve" for $28.00.

Dealer wants $95 and said there are other parts too.

Anyone have any experience with replacing evaporative canister valve or related parts?

Thanks in advance.

PS. Haven't had any diagnostic done yet to come up with a code.

Follow up to above:

Codes that came up were:
P0450 - evap system pressure sensor
P1444 - purge volume control valve
P1446 - vacuum cut valve

Now - what part(s) do I replace?

thank you for the info the dealer kept saying it was my sensor and tried to bill me 798 . I of course said who thsi will help me . being a woman I feel alot of times I get gyped I like being informed I knew my check engine light and the gas issue were connected wait until I tell my knwo -it-all ex-boyfirend who thought I was nuts when I explained my trouble. I now need to know the goingrate to fuix it so I won't get gyped .... ok I like this place already