I have been using a magnetic stirrer for about 9 months. Bought it off ebay for a song. It really does not speed steep like a, ultrasonic cleaner does. However I now use both. I would be lost without my magnetic stirrer. I use it for mixing bases before splitting up into smaller batches too add flavors. I also use it on some stubborn tobaccos with an erlenmeyer flask without a cover, after the UC, to add a little breathing and extra stirring. I don't use heat, I have a thing about high vg content and nicotine with high heat reacting! But to each his own!
If you want heat put you flask in hot water for a while then back on the stirrer.
There are a bunch of DIY videos on making your own with a computer fan and magnets from old hard drives! You can also get a decent used one for around $35 if your patient. You don't need and industrial strength one. Variable speed is all you need.