Maybe, since 5 creds/tgs is the base unit for costing, make it that just as an underlying deterrent to fully decking them out. The Autogun, Shotgun, or Lasgun are all options but you would be hard pressed to have a hay day with kitting your Juves for eventual success, which should represent the value within the gang of the cost of a rifle. This means that Boltguns and Shotguns with multiple types of shot won't be flying off the shelves, but that things are not a set in stone rule.
One big way to open flexibility in the numbers is to use Necromunda's costing system as the base for it. You can't decrease the cost of the worst item, leave that as the frame of reference for the cost of all other items. Then, if you increase the cost per ganger and income earned, you can then inflate across the span of the available weapons and equipment to create pocket gaps between items/item classes, adding a layer of value to the in laid cost system. Managing money becomes more of a factor to gameplay, so adds to the off the table layers of the Necromunda/I'munda system. For one, it reflects the ease of obtaining these items. Combine it with a restructured Trading Post table such as the Alternate Rare Trade Table rules in my link, and the managing of dice result brackets can bring in a tiered system to rarity. If all of this is embedded within the game system, players will naturally arrive at decisions such as "Hmm, does it make sense in the long run to give this Juve a Basic Weapon at the 5 cred/tg upgrade cost?". It would require all the prices to be inflated incrimentally from bottom up, and then recalculate based on the current standard earnings and costings how much the earnings and cost of characters have to be increased to create that monetary balance within the system.