"1013" wrote:

My Avanti Barracuda MTB is due for a new chain since my current chain has
stretched a fair amount.

Is it true that you must replace the cassette at the same time as you
replace the chain in order for them to "mesh" properly?

Depends on wear. plenty of posts on this - look at Seldon Brown's website
for directions

My bike currently has a Shimano 9-speed cassette on it (not sure of the
exact specs). The 05 Barracuda comes with the Shimano CS-HG50 11-32 9spd.

What should I be looking at spending for a new one? Is $100 reasonable? I
assume the more expensive cassette are lighter.

Generally more expensive is lighter, but the current Shimano LX now has the
capacity to remove the sprockets. Could be good for total cleaning, and the
option of only replacing the worn cogs (usually only the smallest), if you
can find replacement sprockets (?)

Are there any good websites to compare chain/cassette prices online?

I found Torpedo7 had some good prices earlier this year for chains and a
cassette.
www.torpedo7.co.nz

But I do prefer the Wipperman chains, currently using the 908 on bothe bikes
with very good wear so far.

Cheers
Peter