Like a fairly fine wine, within reason.

Shopping for a Roomba is like shopping for wine. First, you don’t go to the wine store to be convinced that you should like wine. You either want some or not. If you’re expecting us to lay out some argument about how you should want a Roomba, tough shit. And screw you for trying to waste our time.

So you’re thirsty. You’re scanning the shelves. If you just want to impress your guests by bragging about how much you overspent, today’s deal isn’t for you. If you only want the cheap rotgut, same thing: take your trade elsewhere.

No, what you’re really looking for is the best deal on the best wine you can afford: the biggest difference between the sticker price and the sale price, as long as the sale price is still within your budget.

You could buy the best seller, the Roomba 650. A refurb will run you about $359 on Amazon, forty bucks off the sticker price. Or for a mere $420 - just $60 more - today you could bring home this Roomba 790, which Amazon sells for $600.

It’s way better than the 650. Much more advanced guts. AeroVac Series 2 instead of Series 1, which probably means something. Dual HEPA filters. Three virtual walls instead of one. An extra filter. A wireless command center.

The math is simple. You spend 17% more to get something that usually sells for at least 50% more. If it’s not obvious to you that it’s worth it, we have nothing more to say to you. Except this: next time we have dinner together, please, let us bring the wine.