Yup! A lot of times you see gardening items go for 2-5 TBT per, which translates into 400k-1m IGB considering the exchange rate, even though you see them go for like 50k-200k in IGB.
Buying in IGB saves you money in the long run, and selling for TBT earns you more. Always remember that when buying, especially villagers!
It actually used to be like 100k IGB = 100 TBT when it first started, but a few greedy people wanted more, so it slowly rose to today's 20m+
The inflation of the exchange rate will probably stop at 25m-30m IGB = 100 TBT and stay there, since that's about the most any patient person would be willing to exchange.