DEAR BOB: Last September our realty agent found us our "dream home." It was perfect in every respect. She showed us that it was worth the full asking price, based on sales prices of other neighborhood homes. All that our offer said was "All cash to seller." I thought that was too simple, but my husband felt we should sign before someone else bought the house. The agent assured us that getting the mortgage we needed would be no problem. But it turned out that we couldn't qualify for the loan we needed, and the seller refused to help out with a second mortgage. The result was we lost our $2,500 deposit. Of course, we'll never deal with that agent again. In the future, how can we best avoid costly mistakes like this? Erica M., Laurel.

DEAR ERICA: There are several contingency clauses most property purchase offers should contain.

The financing contingency clause specifies the exact mortgage you need. Never, never, never trust that the loan you need will be available. In your next purchase offer, for example, you might write, "This offer continent upon buyer and property qualifying for a new first mortgage of at least $50,000 at not over 12 percent annual interest, loan fee not exceeding two points, with monthly payment not more than $524.31." If that loan proves to be unavailable, your deposit will be refunded.

The inspection contingency is equally important. Make your offer contingent upon whatever inspections you want, such as termite, structural, or roof. If the inspection report doesn't meet your approval, your deposit is refunded unless you are willing to waive the defect. A good real estate agent can further assist you with contingency clauses.

DEAR BOB: We are considering selling our home. Our profit of almost $90,000 would would be tax-exempt since we qualify for that new $100,000 "over 55 rule" tax break. If you were in our situation, where would you invest $90,000? I doubt that money market funds will continue to pay out such high yields for very long and the savings and loans guarantee their high yields for only six months. What would you do? Cedric S. McLean.

DEAR CEDRIC: I would sell my home and take back a first or second mortgage for the buyer. Recently I sold a rental house by doing so. Mine was one of the few houses for sale in the local market on which financing was readily available (since I offered easy financing).

As a result, it sold in about 10 days for practically my full, outrageous asking price. The wrap-around mortgage I'll carry back will yield me about 13 percent on the dollars I have at risk. Unless Carter's inflation gets totally out of control, I expect that 13 percent return will be a very good return in the next few years.

DEAR BOB: I think you should warn people not to sell their home to a VA home buyer. Last August we foolishly signed a purchase offer which was contingent upon the buyer getting a VA mortgage.The agent didn't tell us we thereby obligated to pay the buyer's loan fee. It cost us $2,450, which we weren't expecting. At the closing, when we refused to pay, the lawyer [TEXT OMITTED FROM SOURCE] that we would have to pay or the sale wouldn't close. You should warn people about this rip-off. Mrs. E. M., Annapolis.

DEAR MRS. E. M.: I agree that VA and FHA mortgage loans fees are unfair. The fault lies with Uncle Sam. The law prohibits VA and FHA home buyers from paying the loan fees lenders charge on such loans. Since the buyer, by law, can't pay, that leaves the seller with the "opportunity" to pay or not accept the purchase offer.

However, your real estate agent should have told you the consequences of accepting an offer from a VA or FHA buyer. You might want to consult your lawyer for his recommendation of suing the agent for the $2,450.

DEAR BOB: I read your recent item about how many home buyers have difficulty qualifying for home loans. To lower the payments why don't the lenders make 40-year home loans instead of 30-year loans? This would reduce the monthly payments so more people could qualify for home loans. David F., Alexandria.

DEAR DAVID: You have a good idea, but it would take a change in regulations for banks and savings associations to be permitted to make 40-year home loans. Since the average home loan is paid off in about seven years, such a change would have little effect on lenders except more potential borrowers could qualify for home loans.

DEAR BOB: Thank you for telling us to be persistent about finding a home to buy. Our agent phoned us last Monday morning about a new listing that had an assumable VA mortgage at only 9 1/2 percent interest. No loan points, no loan applications, no delay. The seller accepted our full price offer, we paid $7,500 down payment and the seller is taking back a second mortgage for the difference. Assuming a VA mortgage is great. Laurie M., Landover.

DEAR LAURIE: In many communities, FHA and VA home loan assumptions are big bargains. But they are hard to find. Congratulations.