Today Bhutan Gandhi FDC issued in 1972 with Plastic 3D stamp was sold only $8. I think this is reasonable value when you compare that it has 3 famous people on it and there are lot of thematic collectors who collects particular person.
Also seller has 30000+ feedback so there is no chance of shill bidding (price increase on their own item or friends/families items) on this sale. This feedback is very important when you buy any Gandhi Philately material as you will have very less chance of getting cheated.
This is just FYI for new collectors so they don't overpay for this kind of item which is frequently selling on ebay. I know there is huge quantity of this Plastic 3D stamps in market so make sure before you buy.
Now look at following Bhutan FDC starting price for auction. Seller's are waiting for some new collector to buy it.
Seller "allstamps4you" from Germany is selling this on ebay at starting price of $45.!!! (Please buy me.!!!, Please new collector, Buy me and regret and quit this hobby!!).
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