I agree - RNA-Seq coverage is typically very uneven (even when working with high quantities of RNA). I think the only way to really do a good job of correcting this is through wet lab sample preparation.
Unfortunately, I haven't seen any data from any such preparations first-hand, but I have heard of developments like this. Hopefully, some of these links can be helpful:
Illumina FAQ (I think TruSeq helps provide more even coverage?): http://www.illumina.com/applications/sequencing/rna.ilmn