Let start with 3212-13A (picture on left side), that are issued on 25 Jun 2004, actually one overprint on number 2670-71 I, from "Monastery" issue, and what is rare in this issue is just perforation. It is perforated 13 1/4. Hardly that common collectors will notice it in any accumulation, if will not search detailed in. And most people will even pass it, because it is in small dimension and not so eye catching, but for specialist it will be great to find it and put in collection. Why it is so rare? Simply quantity issued on basic issue, and just rest or better say leftover are overprinted. Catalogue value it on 600.00 euro for mint or used sample, and on postally used cover is almost impossible to find it. I try to contact my supplier, and response is really grave - no available at present on market, mean - too late for to obtain it.
Same story are with second issue that I see in my collection, it is Michel #3236-38 (picture on right side) dated 10 February 2005, from basic issue number 2607 IIC and 3136-37, also overprint, and here more collectors will noticed it because topic are "stamp on stamp", "transport" and other, here is more quantity issued, and automatically catalogue valued it less, at present Michel have it for 70.00 euro, but dealer will sell it for less, even 50-60% of catalogue value.
I still didn't search my postally used cover accumulation from this country and period, but if I will find it - I will made it on this page visible.