In my opinion, there is not quick, easy cheap way to paint a bike. If you want easy, relatively cheap, good looking and durable, accept the suggestion already mentioned and have the bike powder coated by a professional shop.

Painting a bike requires knowledge, skill, preparation, patience, work and more patience. There is no alternative if one wishes to come up with a nice looking paint job. As mentioned, it will lack durability. It is as simple as that and, believe me, I have painted quite a few bikes with rattle can (lacquer, water slide decals and clear over every thing, then rubbed out)...



or a paint brush (vinyl stickers no clear coat)...