How about finding a triplex pump and a high speed motor and join them together to make a DIY pressure pump, I haven't done it but I guess its possible. I bought a 150 - 170 bar pressure pump from OLX which was engine powered, the hassle of mainitaing the engine, engine oil and petrol was not worth it, sold it and looking for an electric one to be fixed in porch with permanent water connection from the tanky to give a quick bath to car any time at will