Condenser dryers will cost you more to run compared to heat pump dryers. Looking at condenser dryers versus vented dryers, these are around on-par with the majority of models with a 2 Star Energy Rating, however you do get a greater drum capacity in a condenser (8kg) than you do with vented (around 4.5 to 6.5kg), so when viewed that way, they can in fact be more cost effective.
If you’re not using your dryer that often, then go for the one that suits your laundry set up and your living arrangements – e.g. for renters, condenser dryers are great as they don't require a vent to push hot air to the outside. Always use the max spin speed on your washer where possible to help cut down on drying time.
Remember to compare dryers of the same capacity to gauge what the energy efficiency is like, and estimate what the average annual running cost will be by referring to the Australian Government’s Energy Rating site which says to multiple the kWh on the energy label by the cost of electricity in your area.