You can either make money and wear low tier gear, or make a very small amount of money and wear top tier gear, or lose money and wear the most expensive stuff.
Note that WPF dictates how often repairs are made for your weapons.
Paul has previously stated that '... melee weapons are one category for the extra breakchance thingy. The highest melee skill is picked in the script when checking for breakage.' (http://forum.c-rpg.net/index.php/topic,14164.msg199810.html#msg199810)
1wpf is about 11% where as 140 is 2.5% so it does make a difference.
If you are trying to earn money for something, try and keep your gear at about 18K to 30K in total cost. I find that keeping my gear between 10K to 20K allows me to remain competitive yet make a lot of money.
With average luck, over the long run you should be able to sport 30K of gear and still made some money in the long run. Anything past 46K and you will take losses regularly.
A common trick is to wear good gear at high multipliers, and normal gear at the lower multipliers. Remember that every multiplier level is worth about 23K of gear that it can sustain on average.