What do / dont you like about the Sunbeam? And what are you hoping to get out of upgrading? Also, what do you drink? Milk based, or mostly black? How many at a time?
If you want to take a small / medium step to something like a Silvia / Lelit, then you may be ok with keeping the sunbeam grinder, possibly upgrading to the Breville smart grinder. But if you want to take a larger step of upgrading to a HX or DB such as the Minore, youll be restricting it with the Sunbeam. I would go to at least a K3P ($450) depending on whether you want a timer or not. This is in the league of the Mazzer Mini & Macap M4, but cheaper and no frills.
The quip around here is "buy the best grinder you can afford" and maybe you wont need to upgrade your machine at all. Have you got the unpressurised baskets, good tamper, and fresh beans going with your Sunbeam? If you add a K3P to it, you may be happy, which would give you time to save for a HX machine which would last you for the next 5 - 20 years!
Finally, beware of ebay purchases. I would rather look at the "for sale" section here, and make sure the seller is a well known CS member. I bought a second hand in "perfect" condition and it wasnt! An expensive machine may still need to be tweaked, and most snobbers do this themselves with pressure and temperature measurements (or pay for it to be done). At the very least, tell us the ebay item youre interested in and well tell you all the things that could be wrong with it!
Hope that helps, keep the questions coming

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