I think it's usually Trade + Paypal, in which case you can use RS gold when trading, and pay the seller paypal cash. If you don't have any junk, you can get some by:
- Fletching maple longs (u)
- Buying crashing items for lowest price
No when you're buying rares you can offer cash unless the rare you are buying is crashing/really crap then you may choose to buy junk to trade, although it would be pointless
Buying rares is usually the trade price in gp plus a set amount of irl cash. If the person you are trading excepts junk then you could buy crashing items or fletch some bows but junk could be considered just about everything really.
no you dont need junk, all you need is enough gp to cover the market value of the item you want to buy. the irl cash that you are spending makes up for the difference between the street price and the market price.