How to update laminate countertops inexpensively?

Typically the least expensive of all the countertop options.

http://www.formica.com/en/us/products/formica-laminate-home#swatchesTab

I maybe the only person on the planet that actually likes them. I am not a fan of most granite options unless you visit a proper stoneyard and choose your own slab, and the unique slabs are very expensive.

Formica is easy to maintain, takes a beating, lasts a long time with proper care. I have crappy builder special tile and grout and it is horrid beyond belief. I would be thrilled to bits to have formica. Take a look see, then find a dealer / distributor / installer in your area. They look much better in person than they do on a computer screen.

It pays to compare if you have a budget. For not a lot more you might be able to get something a bit better, but don't feel you are "settling" if you can only afford formica.

Here is a comparison guide to peruse.

https://www.thespruce.com/corian-quartz-and-granite-countertop-1822083

New laminate is the way to go

Giani makes a kit to paint them. Contact paper for a make due until you can replace.

Something we have been checking out is using quartz top that is only 1/4 inch thick that sets right over your existing counter, it is much cheaper than replacing them. Also, some people recover their laminates with epoxy. If you click on "make over" on projects, then "kitchen" then "counter tops" there are MANY examples from which to choose. Here is one of those ideas: https://www.hometalk.com/diy/kitchen-dining/countertops/concrete-countertops-32547429

Concrete Countertops

We used a concrete type of finish here: https://www.hometalk.com/diy/kitchen-dining/kitchen-dining-furniture/changing-up-an-orange-formica-countertop-with-concrete-18147786

Changing up an Orange Formica Countertop With Concrete

have you thought about painting? hometalk has an idea...

https://www.hometalk.com/diy/kitchen-dining/kitchen-dining-furniture/painting-over-dated-formica-13563405