Unless they had family money, it's unclear how a married federal-employee couple could afford an $800K/$900K house.
It is possible for a number of reasons. First, they were a two earner family. Assuming that Wilson was a member of the Senior Foreign Service prior to his retirement, he would have been earning around $125K a year. If his wife was either an SES or GS15 or 16 she would be earning over 100K as well. This works out to $225K a year minimum.
Second, one or both of them could have owned property in the DC area. It is common for foreign service employees to own houses in the area and then rent them out while overseas. The USG provides housing abroad or an allowance to rent/own it. There are also other overseas allowances to compensate employess for increased living costs, etc. You can save money from reduced living costs and make money from your rental property. Property appreciation in the DC area has been significant, even in the 90s. The Wilsons could have sold appreciated property to buy up. They also may have invested in stocks, bonds, etc., which increased dramatically during the 90s.
Third, when you retire from the Foreign Service you receive a lump sum payment for unused leave, which could amount to $80 to $90K.
Finally, they could have inherited or borrowed money from a relative.
What I find curious is why Wilson retired with only 22 years service, especially at a time when he was in his peak earning years and his career should have been in its ascendency. I suspect that his career was at a dead end either due to the role he played in the April Glaspie affair or his subsequent performance on the NSC. There must have been a cloud over his head, which "forced" him to get out. With his collossal ego, I doubt if finishing his career out as a bureaucrat stuffed into some cubicle was not acceptable.
I estimate that Wilson's initial retirement salary was around $50K using a high three of $125K times 44% (22 years times 2%) minus 5K for a survivor benefit for his wife. Each year this is increased by the CPI-W, the same as SS. Odd.
Sorry I don't know how to post a link to another FR article, but search out the research done by Fedora on Wilsons Rock Creek corporation and his dealings with Saudis and possibly with the French who were recieving Oil for Food vouchers. I really think all this Rove stuff could be a smokescreen to keep others from asking why the CIA would send someone like Wilson to investigate and also how the media worked hand in hand with all the usual suspects to influence the election.