If you have not yet listed your house for sale and you then find the home of your dreams, how will you take advantage of the situation? How will you proceed? Do you have enough equity to qualify for another mortgage?
Lets look at the "subject to sale" offer from the Sellers perspective;
There is no guarantee of a firm sale in this type of offer for the Seller since it's dependant on when and if the Buyers home sells.
If the Buyers home is already listed and the price is realistic, the Seller may accept tying up their home in a "subject to sale" offer (if not already listed, the Seller may not be confident that the Buyers are serious)
Buyers may be able to entice the Seller into a "subject to sale" offer with a good price. In addition to paying a premium price the Seller will want to add a 48hr clause which enables them to continue to sell the home to another Buyer should they receive another more favourable offer.
In a "subject to sale" offer the Buyers negotiating position is weakened. Buyers can expect to pay more.
Now, if all parties agree to a "subject to sale" offer and if the Buyers are lucky enough to receive a quick offer on the sale of their house, Buyers may find their negotiating position again unfavourable as the Buyers will be under pressure to accept any offers on their house in order not to lose out on the dream home to someone else.
My suggestion is that unless it’s a rapidly rising market; first list your home for sale and then begin the process of shopping for a home.
The advantage of listing first is that when you sell your house you will know exactly what you have to spend on the next home. You can take your time and try to negotiate the best price possible.
You can then act quickly and confidently make an offer on your dream home. Having already sold you will be in the strongest position to once again negotiate the most favourable price and terms.
Listing first saves you money!