Escondido: The SW Escondido toxic site has an underground plume that heads south towards Lake Hodges. I’ve kept my ears perked for a few years on this topic and know some people who live in the area…they seem to be okay with it and suffer no ill effects. You should just be aware of it is you’re considering purchase…not sure how much weight it should be given – that’s up to you.
I think they meet all of your criteria – private, some 1 story, distance from neighbors, no HOA/MR. You may have to be patient to hit your $700K goal though, and not many of the homes pop up for sale.
San Marcos:
Corte Raquel: http://tinyurl.com/77rhc9z
(no HOA, small MR, single stories are well under your price point, some privacy depending on lot)
Duckwalk Road: http://tinyurl.com/87y6tb3
(nice private homes, sometimes under your price pt)
Lavender Ct: http://tinyurl.com/7te9kms
(HOA and MR, but not high compared to Del Mar and CV…nice floor plans too)
La Granada Drive: http://tinyurl.com/6w5gzwk
(no HOA/MR that I know of, nice reasonably priced private single stories)
I know there are other pockets I’ve stumbled across in these areas that are nice and fit the bill, just can’t remember them at the moment…