I just had a camera converted to full spectrum and it cost about that much for the conversion, shipping, etc. So, by that logic, it's a free camera along with the cost of the conversion! I'm not sure what conversion rates are like around you though, so your mileage may vary.
In terms of testing, I don't know of a good way aside from looking at it and/or shooting and looking at the result. The colour of the filter would give you a decent starting point, if it's black it is probably IR only but shorter wavelengths should result in a colour on the filter being visible to the naked eye. If you have some filters from yellow on down to full infrared you could check to see if putting a filter in front of the lens changes the exposure/colour rendering. If a red filter doesn't have an impact, that would mean the built in filter is stronger than red.