There are only a couple of apartments that we've seen open in Malia in April through one operator and the cheapest for 1 week was £183 p/p. Try this website http://travel.creteforyou.com/
which should give you a starter on what airlines/tour operators go to Crete.
It's easier out of season to do flight only and book apartments separately (or stay with friends). There will be apartments in Malia/Stalis that will be able to accommodate you but I don't have contact numbers or email for any.
Beach Road is where you're more likely to find PR work (which is illegal but still goes on) and you'll probably find the owners/managers putting the finishing touches to their bars/clubs in April some may even still be getting renovated. Most people who live in Malia permanently and work the season start around the 1st May.
Once you're there you'll hear of rooms/apartments through word of mouth, just as you'll hear about other jobs...
I know the apartments we stayed at in September usually open for English Easter but they never know until the last minute and they are not on the company's website yet, so if they are open for our Easter they will definitely be open in April. It might be worth your while, if you can, to hold off booking in case more holidays are made available in the next few months