Could the shop getting adjusted to the pskyer class?
I know there are some players that use a lasgun or a autogun, but most people would agree that your secondary should be a staff, otherwise you could play just VS.
Lvl 13 on my psyker and only saw one staff type in the shop, which is the first you get at lvl 5.
In my opinion it would make psyker more appealing for newer player and helps to get a feeling for a staff. Either reduce the level requirement, or increase the chance of buying them.