You know, there is always that other thing- pencil done in the way you're doing it- maybe you need to modify your technique so that the pencil looks good. I mean, digetal is prety, and the flat lines look good, but don't disregard pencil- I still use pencil- coloured or not. Its feels good to draw with, and done right, I like it beter than digetal- see, the problem is  with digetal, that its so easy to skip corners. You say you wont do it, but without a tablet, you will. Its the simple honest truth. It WILL take you forever to get a descent look of shading etc.. on your picture, so if you're going to go digetal, don't rest your life on it. Drawing with a mouse SUX. It doesn't matter what programme you use- you'll never correct that. Its not a natral movement, and even balless mice stick.

Pencil however- as long as you seal it with a sealant, its all natral, weight sensitive, tilt sesitive.... Stuff you're paying how much for to replicate in digetal? Think about your penil technique a bit before canning it. See, even using coloured card for a different medium base rocks my socks. http://www.deviantart.com/view/12118091/ This is a pic I did with dark blue card and coloured pencil. Its different :) Look for sucessful pencilists. Go to an art store and see what they have. Maybe painting would be good. If you want large flat areas of colour, why not water colour, or guache'? That professional, and no where near the price of a new programme and tablet :)