In a logical sense if all it takes are hours or a few days power level crafts to max, then chances are the barrier to entry just isn't high enough. If the barriers to max level crafting are not high then just about any player will be capable of raising their crafts to max level in little time. Not to mention, as more and more crafters enter the economy, the supply of goods will increase causing the price of goods to fall. At some point it won't be cost effective to produce many items.
So in any case if you can sprint to the finish on trade-skills, by all means avoid spending your money on them. Otherwise, you'll find yourself similar to the millions of college graduates who were suckered into the false hopes and dreams of a good paying job, but instead were stuck with a huge debt and not-so-worthy college degree.