I highly doubt you will find a completed boat for that amount of money. Generally a fiberglass hull runs from $100 to $150. A used boat will probably run between $500 to $800. And that is without a radio system.
The price of a warship will always depend on the seller. A small 1 or 2 gun ship might run about $400. The larger the ship the higher the price. Most used boats are sold without radio systems.
I do have a ship that is 200.00 and one that is less. The ships are not complete but close to it. Mogami is a spare ship that i have and it needs work. it runs, but needs guns, co2, and radio. the cargo ship is 150 with radio, the ship needs to be patched and the radio needs aa batteries but it worked well last year.
I'll probably be selling a completed, armed WWI armoured cruiser this summer when a replacement ship is completed. Like all of my models I made the fiberglass hull and glassed a fiberglass deck to the hull so it's a strongly built unit. HMS Minotaur is equipped with 3 BB cannons, of which it can use 2 at once. It can be battled with dual stern guns or a bow and a stern gun, and can be used under Washington Treaty or IRCWCC rules by switching props and pump outlets. The Defence Class were the biggest British WWI armoured cruisers. The model is unique, with no other 1/144 fiberglass Defence Class hulls in existence. The hull is a stretched version of my HMS Duke of Edinburgh hull, now sold by Strike models. It will be sold with everything except the radio and receiver and has 4 Futaba servos (pump, rudder, throttle and guns). Cost will be in the $600-$700 range. Bob