Ericson 32 or Islander 32 MkII or ?
Neither boat are really may idea of a good candidate as single-hander nor "Upgradable for passage making in a couple of years." Both boats started life as coastal cruisers and so are a little bit lightly built and really not engineered for serious passage making. It is not that a light weight boat can''t be a good offshore boat, but a light weight boat needs to be carefully engineered for offshore work and these boats aren''t (at least the Ericson 32''s that are likely to be in your price range.)
Both boats use hull forms popularized in 1970''s era IOR boats (pinched ends, deep canoe body, and wide beam at deck level). This is a hull form that has been widely criticized in the aftermath of the Fastnet Disaster as being far less than ideal for offshore sailing.
Both boats employ the typical IOR inspired sail plan as well. This rig employs a very small high aspect ratio mainsail and big genoas (especially with the typical winds in San Diego). This is not a very good rig for single-handed cruising. The proportionately large jibs are hard to tack short handed and cannot be reefed down to as small a size as would typically be needed in a real blow and still hold a proper shape, so you need to be able to make sail changes. It is next to imposible to make sail changes on a roller furler in high winds single handed. As someone who single hands a lot, I strongly suggest that you look for a boat that has a rig with a proportionately larger mainsail and proportionately smaller jib.
Depending on the year Ericson 32 the quality of build on the Ericsons varied pretty widely from pretty poor to quite good. Supposedly the build quality went up after Pacific Seacraft started building the Ericsons but those boats will be closer to $50-55K. The Other issues with the Ericson is the lack of a seaberth in the main cabin and the small water and fuel tanks.
Islanders never were all that well built although there was a definite improvement in quality by the early 1980''s. The Perry designed Islander 32 has a better distance cruising layout (but not as good a live aboard layout) and certainly better tankage than the Ericson.
In this same category you might also try to find a Sabre 34, C&C 32 and 34, Pearson 10M, Mirage (Canadian not Florida Mirage)33, Sigma 33 (probably my favoriet on this list for what you want to do),Aloha 32 (probably the best on this list for offshore work)Dehler 9.8 (I have always liked this 32 footer), Ontario 32, Hinterhoeller Niagara 31, and Southern Cross 31 (Ryder).