SOME SUGGESTIONS - With all these different variables, you may be wondering what the best settings are to achieve a good balance in your game. Of course this will depend on what you want. Many people (myself included) like to make trade more difficult. I also like to set the barter settings relatively close to de-emphasize Speech skill and place more importance on the Speech perks.
Fluctuating Gold - This option will add an additional random amount of gold to merchant inventories so that merchants don't always have a static amount of gold. This will be added to their base gold, so they will always have at least the base amount available. The random amounts have been set with regard to the vanilla gold amount and won't increase merchant gold drastically above the vanilla amounts.
LITE VERSION - This version does not require SKSE or SkyUI. It does not include the changes to the barter settings, merchant respawn times, or the VendorGold lists. When installed, this version will activate automatically and uses the mod defaults for its settings. Please refer to the included README for full description of what is and is not included in this version.
Bartering services is best reserved for when you were going to make a purchase anyway. So instead of bartering your dog grooming services for an emergency plumber, you could establish an agreement with your shampoo supplier. You know you're going to need shampoo to run your business. So offer to perform a pet pedicure in exchange for an equal value of shampoo each month. 

mid-15c., apparently from Old French barater "to barter, cheat, deceive, haggle" (also, "to have sexual intercourse"), 12c., of uncertain origin, perhaps from a Celtic language (cf. Irish brath "treachery"). Connection between "trading" and "cheating" exists in several languages. Related: Bartered; bartering. The noun is first recorded 1590s, from the verb.
PERKS - Trade & Barter allows you to adjust the value of the Investor and Master Trader perks. This should work even if you have another mod that alters the Speech tree. Options: set either perk to 5000 max. You can set independently adjust the amounts required to invest and the amount of gold the merchant receives. However, when you make the initial investment, this money will be available until spent. Trade & Barter also adds to the Investor Perk by providing merchants with increased inventories when you invest in them. Increased inventories are unique to each individual merchant.
In his analysis of barter between coastal and inland villages in the Trobriand Islands, Keith Hart highlighted the difference between highly ceremonial gift exchange between community leaders, and the barter that occurs between individual households. The haggling that takes place between strangers is possible because of the larger temporary political order established by the gift exchanges of leaders. From this he concludes that barter is "an atomized interaction predicated upon the presence of society" (i.e. that social order established by gift exchange), and not typical between complete strangers.[14]
I wish I came up with this fantastic idea. SharedEarth is a free site that connects landowners with gardeners and farmers in need of space to grow crops (i.e. starting a home vegetable garden). You can find free access to land in exchange for sharing a little bit of produce with the landowner. In a time of a strong and growing local food movement and concerns about food safety, SharedEarth might just be the most important sharing site of all!