Please don't do the dowel thing. This has come up before and long-story-short: it's a bad idea. I'd consider going for the real solution: either a suspension fork with lockout capability or swap over to a full-rigid suspension-corrected fork if you know for certain you will never need suspension.

Surly is a good manufacturer of rigid forks. Another one to look at is the Kona Project 2 which sells for around $60. If you're looking for a cheaper solution, try a fork from Tange. Althugh, I'm not necessarily promoting the following online shop, I would suggest you look at their webpages to give you an idea of what's available... http://www.bikemannetwork.com/biking/c/COMPFKMTNR

Note that the critical measurement you will want to pay close attention to is the axle-to-crown (AtC). You should choose a fork that closely matches the AtC of your current fork in order to preserve the handling traits. Picking a fork with a shorter AtC than your current fork will both drop the front end, increase the effective steepness on your headangle and also quicken the steering. A fork with a longer AtC will raise the front end, decrease the effective steepness of your head angle and make the steering more lax.