I’m looking to make an effective ad in the local newspapers to hit Buyers and Sellers. Does anyone know of a place I can use for some inspiration or just copy some good ads that are known to work?
I would think combining those two marketing goals would just clutter and confuse your message. Why not separate them into two different ads so you can focus on each category?
I agree, this is not a good use of your ad space.
You need to have a clear, focused message, not “I buy houses, oh yeah and I sell them too” 
With that said, you could use a website address in the ad as long as the url is short enough. Then, if you have both buyers and sellers see the ad they may both go to your website and do their thing.
I use my website address in ALL of my ads, offline and online marketing.