Matt,
Are you planning to develop the property yourself or bring in a development partner? What does your zoning allow for total number of units you can build on the 5 lots? Do you have to re-plat them, or are you looking to maximize your zoning on each individual lot? What's the cost to actually connect to and use the utilities, how much are your tap fees? I am assuming your $50,000 cash is after you've purchased the 5 lots for $20,000, are you planning to use that for construction financing and is the bank offering those terms for construction costs? If so, how many "nicer units" can you built for around $300,000? If construction costs are similar to anywhere else in the country right now... you need a well capitalized partner to truly deliver highest and best use. Make sure you understand your costs of the entire project before closing on the land. Land doesn't deliver long term passive cash flow unless it has something rentable on it.
-Sarah