It is obvious that the weapons other than the highest quality Q7 is useless even they cost less per hit. They (lower quality weapons) increase your damage much less compared to price difference (value of money is much less in return). More over people are aiming to use less weapons these days compared to increased production of weapons (supply and demand are not balanced).
My suggestion is letting use of different quality of weapons at the same time one from each to add up and increase your damage say 200 % for q7 + 100% for q5 and 20 % for q1 weapon in total of 320% damage increase. If the shooter has all quality of weapons in the stock and clicks on them in the menu of weapons selection to use them at the same the total increase will add up to 200+120+100+80+60+40+20 = 620% damage increase which will cause a lot of increase in low quality weapon sales those are seem to be dead atm.
A little different approach can be applied to food where somehow combined food can become a 10 or 20 hp energy bar or
such combined food usage can decrease the time required to generate energy or increase the amount of regeneration. These will increase the usage of food per person and end up with a live economy.
