An instrument for strobe fountain mainly consists of two parts: (1) something which can put vibration with some frequency to water, and (2) a flashing light with some frequency.
In How to create an instrument for strobe fountain, an oscillator and a stroboscope are used for (1) and (2), respectively. But, they are not so cheep, several hundred dollars, because we can change their frequencies so we can see different animation like phenomena.
If we give up this functionality, to change its frequency, for an oscillator, then all we need is something to give vibration. So we can use any products with a motor. Here are some links to such products on Amazon.
We've checked that we can see strobe fountain with an electric lint remover. We bought it for only 100yen, about a dollar, at a dollar shop in Japan.
An expensive stroboscope has intense light, so strobe fountain by such a light looks beautiful. Here is a cheep stroboscope costing about $50: Deluxe Digital Stroboscope