Well there isn't likely to be much auction activity for 1/2 cent orange stamps. But somebody must buy and sell these stamps somewhere. Whatever the case, I've got a few of these italicized stamps and three are posted below. The half center was mostly used for paying the tax on low budget insurance policies. Without doing too much research you can tell the above stamp was used by an insurance company. The stamp also has a nice clear guideline running across the bottom of the stamp.
All of these stamps were cancelled in the first year of use of the 1898 series, more than a year before the half cent gray stamp became available. The relative scarcity of the orange stamp in used condition must be a function in part of complete withdrawal from use of the orange stamps as soon as the gray version became available.
As in a previous post, all the half cent documentaries were printed before hyphen-hole replaced the roulette. All oranges and grays appear only with roulettes.