Permanent Residency...detail clarification plz! (Brussels)

My husband and I are trying to become permanent residents of Belgium as soon as possible with an eye to retiring there as Belgian citizens. We are trying to get answers to several questions about the correct bureaucratic pathway: Can entry on retirement visas lead to an unrestricted permanent resident status? How do we show real ties to Belgium? Will purchase of a home there with a mortgage accomplish that? Do we need to start a business to show the real ties? Etc., etc. We think that we need professional advise, but are reluctant to contact a large Belgian law firm because we don't want to spend 15,000 euros to get answers to a few questions.

Has anyone had experience with this set of questions? Can anyone recommend a reasonably priced Belgian immigration attorney?

Thanks.