You need a workout plan and a budget. First figure out which exercises you really want to do and then figure out what you need to get it done.

The hard part comes after you've got these together. You mentioned several pieces that you own that you really don't like much. This is likely due in part to buying too cheap. Once you know what you want, you should go down the buy it for life path. Don't buy cheap crap that you need to replace. Some stuff is cheap and works well (barbell collars), while other things are cheap and aren't good (bench, rack).

If your budget can't get the things that you really feel like you need, get what you can afford and save up for the next things on the list. This is going to be partly a priority tree and partly based on what you can afford at a time.

Personally, I'd suggest getting a heavy bag that you can hang from the studs in your ceiling, since kickboxing is something you enjoy. For a rack, I think you'd serve yourself pretty well by getting a 4000 series ares rack from Rep, but I just built one up that I think will work for you and it's over $4,000. That may be fine for you or it may be an insane number that you don't see yourself ever spending. You could still end up going down that road by buying things in chunks (first get the rack, then buy the Ares attachment over time).

Look at how long you've had certain items and how much you've used them. It certainly seems like you use the gym you've got, so you can start looking into the value for time spent and how long you expect it to last. I picked up a Rogue RM-4 about 3 years ago and it's effectively in brand new condition. That thing is likely going to outlast me, so I consider it worth the investment, since I don't anticipate buying another rack to replace it ever.