About a month ago I purchased a FeelTech FY6600 60Mhz dual channel function generator. This is a very capable little device for audio and RF design/test at a cost under $90. Combined with a descent scope the uses are nearly unlimited. The link below has a complete description of its wide range of capabilities so I wont repeat it. A google search will show many suppliers, some in USA and Canada, with differing prices. There are also some good Youtube reviews. Check it out.
I mention this for info only as I really like mine and other builders / experimenters may find one valuable also.
https://www.ebay.com/itm/28276172484673s Nigel