Hebda,
I tried the 70s and the 888s for a week. I could not get a good fit with the 70s, so the sound I experienced was not as a lot of people have described. Since I did not get a good seal, music sounded distant, bass was tinny and non-existent. I was not about to shove the 70s further into the ol' ear canal.
I fell in love with the 888s, great sound nice bass and good controlled highs. There are a couple of mods that were posted on Headwize to tweak the sound. One involved taking the caps off a set of Sony Groove buds (forgot the model number, contact Vertigo-1 for details or search Headwize once it's up and running again) and replacing the caps on the 888. By turning the Groove caps a certain direction the bass response was improved, to some greatly. Cost no option $50 - $80, get the 888s.
A low cost alternative are the Sennheiser MX500s, for around $15- $25. Not as detailed as the 888 and the bass not as clear, but nice sound for the price.
Regards - reynman