There are a few concepts here a bit mixed up:
a) Token value vs token cost
If it's about value, the token price is linked to an offer-demand balance determined by the market, so nothing related to the cost of minting it.
If it's about cost of generating the token, you could define a minting function that starting from token 101 (by looking at a counter), you could add random read/write operations to consume gas and therefore, generating an additional cost to execute such as transaction.
b) Transaction cost vs. Mining complexity
When you increase the gas consumption to execute a transaction, the one who is paying for that gas is the user executing that transaction, not the miner.
The mining difficulty is managed through other parameters and miners do normally pick up transactions based on the total gas price per transaction (the higher it is, the more likely to be chosen), rather than only on the gas amount.
In summary, I kind of guess that you want to release a pre-sale offering so that the first buyers can get tokens at a lower gas consumption. If that is the case, you can do the approach of adding random operations to increase the gas cost. However, it would be easier that you just define how much ether you require to buy the first 100 tokens vs. the rest of tokens.