Hey, if my paranoid-to-wireless character can buy (or steal) a cheap deck so the smartgun and enhancements work right...
Cheapest deck is supposed to be 50k. However, as I understand it the basic difference is that a deck has Sleaze and Attack attributes, whereas a commlink does not - both, however, provide Data Processing and Firewall attributes, the latter being what's relevant to securing your stuff. However, getting a deck might be enough to let you run silent effectively - or perhaps some skill is needed.
You could probably still manage a decker/sam with Resources A, Attributes B, Skills C, Meta D, and Talent E; Attributes to Logic, Agility, Intuition, and lower Charisma. Full freight of negative qqualities, karma to skills. You might be able to swap Attributes and Skills around and going karma to attributes - hard to say for certain which is the better choice.