What do you think would be the best use of a .5 acre lot in central Austin?

I am thinking a condo regime with 4 units however I am not sure if I can get the financing needed and am not familiar with local builders. 

I don't think you can put 4 units on SF3. Only duplex, from my understanding.

Hey @Nick Valo ,  @Andrew Allen is correct. That lot is zoned for SF or duplex. 

It’s a good bet that condominiums will bring you your highest return. You may want to find out the feasibility of subdividing the lot. Then you could potentially build 4 condos.

@Nick Valo That is a tough question without knowing more information about the lot. What is the highest and best use for that lot? That depends upon the location in central austin and the demand for space therein. Central Austin also includes downtown. The highest and best use for a half acre lot in downtown Austin is probably not condos. Without knowing more about the property its hard to determine. Can you change the lot to a commercial lot? Can you make it retail? Can you subdivide it? There are a bunch of unknowns, imo.  

Agreed, if you want to build 4 units on an SF3 lot, regardless of size, you'd need to subdivide it. That would take a minimum of 65 feet of street frontage, and up to 70 feet in some cases. Most SF3 lots don't have that much frontage and won't be eligible for subdivision, so you're more than likely limited to a main house and an ADU up to 1,100 sf, or a duplex. You can sell either option separately via a condo regime.