One recommended strategy is to focus on mid to high cost domains and sell them in the long term for a very high amount of money. After all, your only yearly cost is a few dollars.
However, it can be more interesting financially to focus on low cost domains. Their resell value can be a lot more, provided you buy only domains which have got a real value rather than simply gambling.
Just consider buying a domain for 50,000 dollars and selling it for 75,000. You made 25,000, however this is “only” 50% profit.
On the other, it is quite easy to sell for $100 a domain you bought for $25. In that case, your return is 300% and on top of that, it was a lot easier to find a buyer and you did not have to negociate for months.