In this paper, we present a hardware-software co-synthesis algorithm, called COWLS, which targets embedded systems composed of servers and low-power clients which communicate with each other through a channel of limited bandwidth, e.g., a wireless link. Clients may be mobile. COWLS allows both hard and soft real-time constraints. It simultaneously optimizes the price of the client-server system, the power consumption of the client, and the response times of tasks which have only soft deadlines, while meeting all the hard deadlines. It produces numerous solutions which trade off different architectural features, e.g., price, power consumption, and response time, of an embedded client-server system. As far as we know, this is the first co-synthesis algorithm of its kind. We present experimental results of synthesizing a low-power, client-server camera system as well as several randomized examples.