Humidifiers and Dehumidifiers - Wiring DS-3200 humidifier with R8222B relay

I bought Desert Spring humidifier DS-3200 and would like to conect it so it runs only when furnace is in heat mode. I have Regal REL-750 furnace with Beckett oil burner and R8285A Fan Center with SPDT switching action including R8222B relay that controls the fan motor. From reading the posts I found out that I can make it work if I buy A50 relay, conect it to the COM wire on the fan motor and get my 24V of R8222B relay. Can I conect humidifier without buying A50 so it works only when hot air is blowing? When I tested R8222B relay I have 26V betwin R,C and R,G all the time. There is no HUM conection on the furnace. My termostat is just for heat and conected to the burner 24V. I don't even need humidistat because my house is double insulated everywhere and furnace works very seldom but when it does we have very dry air. Thank you for your help!
P.S. If I need A50 relay, what store can I buy it from besides the internet?

You could get the A50 from a heating and A/C dealer, or some hardware store may have it, but I never seen it around here, and never seen it at home centers.

I would still add a humidistat, don't want you to over do the house, or you may have some hidden damage down the road.

You can go off of R, go to the A50 relay, humidistat, then to the humidifer, and back to C.

Thank you Jay!
Ok, after reading your msg I just bought the "24 volt current sensing relay general aire GA50" from ebay for $23 including shipping and will instal a humidistat and connect it the way you said. Thanks again.