A power rack or cage is usually considered one of the “must have” pieces of gear for a garage gym. I love mine and it brings peace of mind while back squatting and benching. I also use it for overhead pressing, pin pressing, pull ups, dips, etc.
But… if not doing a lot of barbell stuff where you need the safety, or the pins to press off of, then a rack is not essential and might be further down the list of nice to haves than it seems.
Rather than a rack + barbell, consider a good incline bench. You can use that today with the dumbbells for various movements. If you add a cage/rack later you need a good bench anyway. I like to have both a good incline bench and a good flat bench in the gym. But a good incline is more than enough. Like bicycle contact points, don’t be cheap. Get a good one.
For pulldowns and rows, the rack attached units (like Rogue slinger or Spud pulley) aren’t that great IMO. I have a Body Solid GLM83 model Lat Pulldown / LowRow plate loaded machine. It was something like $400 when I bought it and is $600 now. You can do a ton of different movements very effectively with a high / low pulley machine.
A step up from something like the GLM83 would be to get something like a single pully selectorized column. With the right accessories you can do all sorts of great functional training movements plus lats and rows. I’m adding a Sorinex single column to my gym. It’s not easy to find on their website, but they make accessories to enable lat pull down + low row on the column. As long as you don’t need huge amount of weight for lats and rows it works a treat. With selectorized machines the pully ratio is important. If you need more you can add bands or a GymPin. Am guessing most of us on TR are not monster lifters so 300# stack even with 2:1 ratio is not a limiter.
For leg work, back and front squats gets the attention, but consider something like a belt squat set-up instead.
I find Hypers and GHD movements to be important. You can do those off a bench with bands, but a proper machine is nice to have. These run in cost from not bad to stupid expensive.
TL;DR - While the rack gets the most attention, I’d say for cycling and functional movements there are better ways to spend the money. If you are going to be doing the powerlift movements, then get a cage. YMMV
If I were setting up a gym to focus on functional strength and fitness I’d have:
Dumbells 10-75 pounds (powerblocks work too but I like good old hex dumbbells)
Kettlebells in 3-4 weights
Incline bench
Step up platform
TRX or other web system
Selection of bands
Functional cable column, single pulley adjustable
GHD/Hyper machine
Olympic barbell with 300#
Power Cage
That is likely going to read backwards for a lot of folks. As I get older and more focused, I value the functional strength and core work more than the powerlifting moves (bench, squat, dead, OHP).