I don't think Gandhi Stamps or Gandhi Sheets are for investment.!!
Update on 12/15/2011 :
Check out price of recently sold Malta Gandhi FDC and no one willing to buy block of 20 Gandhi Malta stamps even at $4.99!!
Reason for this low value is because there are lot of Forgery and FAKE stamps and philatelic items related to Mahatma Gandhi stamps from India as well as other stamps of India.
It's not only stamps from India but also other countries also. Read following link to understand what's going on.
1) Nicaragua FAKE First Day Cover with Gandhi and Einstein Stamp.
2) Madagascar Forged FDC with Gandhi stamps.
3) Fake cancellation on Panama Gandhi Stamp to make private First Day Cover.
4) Forged 1948 Gandhi First day cover with stamps from India.
So think before you buy. Just don't buy if any philatelic magazine, book or website praise about it to glorify Gandhi philatelic material. It's in your hand.!!
So how can we even trust all the philatelic material with stamps from India. To me it all looks BOGUS to make money from collectors by selling lot of FORGED in 1948 Gandhi Philatelic used covers, register cover and even First Day Cover.
1) 1948 Stamps of India are False hope of Riches?
2) 1948 Gandhi Stamps of India: Are False hope of Riches - Part II ?
3) 1948 Gandhi Mourning Private FDC : Are False hope of Riches - Part III?
4) 1948 Expensive Gandhi FDC : Are False hope of Riches - Part IV?
5) 1948 Gandhi Stamps Early Usage cover : Gandhi Stamps Are False hope of Riches - Part V?
6) Maxi Card sold for $5100 with 1948 Gandhi Stamps - False hope of Riches - Part VI?
7) Indian Philately Exposed
8) Indian Philately Exposed - Part II