Erlangen- new to the area

I don't know the Erlangen area, so the following is only general:
Engaging a realtor is of course optional, but might help if you are not familiar with the German property market, it's rules and conventions. Also, if you have a limited time to find a place, the service might be indispensable.
For rental contracts, the realtor charges the party who engaged him first (usually the landlord). For purchases, the buyer has to pay his fees (usually 7% of the price).
Properties available without realtor are often posted on Quoka and Ebay Kleinanzeigen, while realtors often advertise on Immoscout24.
Given the high cost of purchasing real estate here (around 7% of the price is due as taxes and various fees - the realtor fee not included!) and long lead time for any sale, you should only buy if you are sure you will stay there for a long time. If unsure or planning to stay less than, say, three years, renting is a better option.
Property prices here are also moving too slowly to enable short-term speculation: 3-5% yearly increases are possible only in a few, booming cities and only during good economic times (on the other hand, property prices in Germany rarely ever fall).