Spatial audio systems are expensive, mostly because they usually imply the use of a wide range of speakers and hence audio outputs. Some techniques such as Wave Field Synthesis (WFS) are especially demanding in that regard making them out of reach to many individuals or even institutions. In this paper, we propose to leverage recent progress made using Field-Programmable Gate Arrays (FPGA) in the context of real-time audio signal processing to implement frugal spatial audio systems. We focus on the case of WFS and we demonstrate how to build a 32 speakers system that can manage multiple sources in parallel for less than 800 USD (including speakers). We believe that this approach contributes to making advanced spatial audio techniques more accessible.