In our Honegger 2011 catalogue we did write about the values of mixed frankings of “Ortspost” and “Poste Locale “with each region rated. Find same (amended) table in the Swiss Postage Stamp Catalogue 2015, the Swiss Federation of Stamp Dealers publication.
The reviews require an explanation:
Basically we have made the same assumption, with which we have rated all other imperforated issues of classic Switzerland in the catalogue: The catalogues prices are only valid for very nice and very fine pieces. That also applies to the reviews of mixed frankings. We have for example a quality of a very well preserved mixed franking in front of us on a poorly preserved cover or with an ugly stamp, so you will be glad to expect only 50 % of its catalogue value. But when also the condition is only poor or moderate, the price for such a piece is only 20% or even as low as 10 % of the specialized catalogue value.
For example, we see this very well when we look at normal cantonal covers. A Zurich 6 or a Geneva Eagle or a Waadt (Vaud) 5 in defect condition but also not on a pretty cover, we can pay for this without any further explanation about CHF 1.500.-or maximum CHF2.500.- If the stamp has further defects, the price goes down to CHF 500.- to CHF 1.000.-. You can value the mixed frankings in the same way.
However, we do not have only one valuation but look in our filing records how many covers exist with such a combination. It can happen that you come across a rare or even rarest combination, of which are known only a half a dozen. If now all these stamps of the combination are in poor quality, you can deduct that there are no impeccable deluxe pieces and you can use the catalogue simply as a guideline although that valuation can never be reached.
You can see from our documentation that we did not only list entire covers but also fronts on condition that they show a clearly dated cancellation on the piece. This was foremost for the reason to exclude any discussions whether it was an entire with or without content or only the front or only a part of the letter.
All this is not always clear when simply looking at a photo, which questions we tried to avoid. It is advisable not to give an exact valuation for mixed frankings of less known combinations and to treat them with great precaution, if it is not clear how good and nice the condition is and whether this is a cover or only a front.