You could spend $120 on a pair of the optimum Bilstein replacements, and then pay another $200-300 to a shop to change them. You run the slight risk that the Monroes allow the front to sag so much over bumps that your wife notices them hitting the bump stops, and you have to adjust the headlights. Take before and after measurements. Only you know whether the risk of $144 is worth saving $400+ to do it right. On a SWB vehicle, it would be a much easier decision. Or you could call shops and see if they know trailblazers and can give you a quote on replacing the shocks if you provide the parts.
It's also not unheard of to take the struts off the vehicle yourself, and take them and the new shocks into a shop, and have them use their beefy wall-mounted spring compressor to do the swap for $50. Call around.