Which harps stay in tune longest?

[Thomas Hinkle <hinkl_th@xxxxxxxxxxxxxxxxx>]

I'm inquiring as to which brands of harps(diatonic)  are preferred out there.
I've been buying a lot of different harps in the 20-30$ range and have
been trying to determine which are the best.  I like my special 20 pretty
much.  I bought a Marine Band because I liked it's sound (although often
it seems like I credit the harmonica with a change in the tone when it's
just something different that I'm doing) but anyways, after three weeks or
so of hard playing the four draw is so out of tune that it hurts my ears. 
So anyways, that pissed me off because don't have much money and I hate to
lose my harp so quickly.  So, I ask you, which harps stay in tune well?