KYB GasAjust monotube shocks are reasonably firm and do not wear out; I've got 270K on mine and they're still working well. A cursory google search shows
ShockWarehouse has a set of 4 for $233. They also have the KYB Monomax model available (complete set for $285); these are significantly stiffer.
I've used the GasAjust shocks and struts over the years on my RAM, F150, Formula 350 (shocks and complete front struts) and 200SX (shocks and front cartridge insert), and always got good service and a good ride from them; the rides on the Fireturkey and the 200SX were fantastic with them.
Don't even look at the GR2 model; they're twin-tube and wear out fairly quickly, as do all twin-tube designs. I made this mistake once on my F150.
KYB's phone service was quite good the time or two I called them, they gladly spent the time walking me through the models helping me determine which ones to buy, and then looked up a local retailer for me.