Painting a bg 0.0, sounds like a big amount of work and I am to lazy for that ^^ haha joke :P
Thats why i brought my tablet to eventualy paint my own bg but than it wil take to much time to put in 1 tag. A ps speedpaint takes like 12 hours + another 2 hours for the tag its like a day job :P
I think stocks are a fair way to start a signature. People made them for you so you dont have to do those 12 hours of painting, and start directly with the focal. There are easy ways to make your own bg to. Grab a photocamera go outside and take some nature shots. and there u go add some blur and maybe some painty line's in it and it looks like u made your own paint BG. ( You made it to becouse its your photo!) Or make your own space stock. DA is full of tut for that. go outside take a picture of the clouds mess around with it in ps add some fo your own stars and feeling in it, and there u go you have your own space stock in like 1 hour. Just some idea's :P

And syn i have to disagree with you :P
They might be cheap becouse you didnt made them, but the posibilities you have with c4d's are endless i havent seen 2 tags that are like completly the same with c4d's in it. And to place the c4d take's a lot of time and skill to (maybe not that much skill :P) But to get it look right like slave's tag above here with the face. that is just awsome it looks like the is half human half c4d and i love that tag ^^
just my opinion on your opinion :P

I dont think we should make evything ourselves. after all these are only signatures we make for fun. Its not like we are making art that would be viewed by 10000 of people and offending us of using c4ds..
I am happy they exist, helped me out a lot few months back.