An REO (Bank-owned) property at 584 Galsworthy Street (1,245 sf) already has an offer accepted, pending removal of the Buyer's Contingencies. Another home, West of Moorpark Rd. & North of Janss, is for sale by a regular seller (with Full Disclosures) in turn-key condition listed under $600K. When you are dealing with almost 1/2 acre parcels, the appraisal will naturally come in substantially higher.
There are a lot of variables in your question. What size home? (The smaller the house, the higher the $/square foot). What size lot? Large is a relative term. Based on current comps, you would be looking at $300-$350sqft, w/a min. house of 2,000 square feet, on a min. 15000sqft lot.. But again, lots of variables. Call me! Let's review exactly what you're looking for.
According to the MLS this evening, you're looking at approx. $250.00/sf, based on an average structure of 1651 sf and a lot size Minimum of 10,000 sf. Actual stats from (9) listings are shown below. You'll notice in the link provided that all properties need TLC (that's more than Tomatoes, Lettuce and Cucumbers :-D)
Quick Stats - Averages
Listing $ SqFt Listing Pr/SqFt DOM $ Selling Pr/SqFt
Residential (9) $422,155 1651 $269 26 $426,200 $254
Good luck in your future home search!