DO YOU WANT TO BE RICH IN YANILLESCAPE? Well heres the guide so you can be!
STEP 1: To start merching you will need either good items already or money to buy cheaper stuff, like dragon boots dragon chain etc. The whole idea of merching is to buy an item for cheap and sell it for more, thus making a profit. I would suggest merching dragon boots at first because they can vary in price(50m lowest usually and can be up to 150m for players who really want them). I would suggest getting a pair of them or having enough money to buy a pair.
STEP 2: Now that you have dragon boots you need to sell them, let's say you bought them for 65m, try to sell them for lowest 75m and as high as someone will buy them. do this over and over until you have a billion coins or a little more.
STEP 3: Since you have a billion coins you can now merch better items! Making a much greater profit, i suggest buying ancient staffs for 200m ea, then sell them for 300m or more(which mages will buy for that much and sometimes more :D). Now since you are making so much money you cant hold onto more then 2.3b cash, either convert to castle war tickets or buy tassets which are worth 1b, 99% of the time they aren't anymore or any less.
STEP 4: now you might have 10-12b, you should go an buy a pair of dragon claws, now trade these claws for a bgs(bandos god sword) which is 8b but is not as used as often as the dragon claws. now do the same and buy one more pair of claws then trade for a bgs. now u have 16b of items. u can trade these 2 godswords for a party hat(most likely the white one which is 15-20b) and then you should do do this same process just with more expensive items and make more money.
STEP 5: Now i think you should have the hang of merching and the prices of most items, so get out there and keep merching!