I think you hit the nail on the head then. DJs are often gearheads and the vast majority of the time we buy equipment because 'we want to' or because 'we fancy a change' rather than because 'we really need that in order to do our job'. Then we try to justify it.
Having spent thousands on gear over the years I never ever use, here is my current way of looking at gear purchases.
1 - do I need this to be able to continue what I'm doing (i.e has something broken an needs repairing.
2 - do I need this in order to offer something I am currently unable to offer (and if so, I do a business plan)
3 - Can I afford it or will I need to finance it and if so how?
4 - Is the purchase to upgrade what I do now e.g. better speakers
5 - Is the purchase to replace something which I have but no longer need/use
Those are the main purchasing criteria for me and each one then launches a process. So - for you I'd suggest:
1 - How many 'club style feel' gigs do you currently do, and are they well paid?
2 - How far ahead are these gigs booked usually?
3 - What percentage of these gigs make up your total income?
4 - Is this a market you actively wish to persue?
the thinking is - if you only do a couple of these gigs per year then it is crazy to spend good money on gear. Hire it or borrow it as you need it. If you do need to buy stuff but the gigs are booked 3-6 or more months in advance then dont buy till you need to. Get the bookings first, have some money available in your account and then buy.
If these gigs make up just a tiny percentage of your bookings and it is not a market you actively wish to pursue then simply turn them down. Learning which gigs to say no to is a really important part of being a professional DJ.
If these gigs make up a large part of your bookings or is a market you want to actively pursue then consider not only the lighting but that you might need tot otally rethink your audio. Personally I turn down gigs for 250+ guests unless the clients have the budget to cover hire costs. Generally though I dont do them these days. I also turn down all enquiries which arent for weddings/renewals/gay weddings etc. I dont do christenings, bar/batmitzvahs, birthday parties, karaoke, race nights, kids parties and so on.
I appreciate you cant always specialise straight away but it is worth setting limits and targets for the types and size of gigs you want. 'Club Feel' lighting is a very subjective thing and generally we cant screw lights to the ceilings all around the room so some creative thinking is called for. A simple set of moving heads and some LED washes with perhaps a strobe if that is your thing will cover it - but start getting some bookings under your belt first.
I have 4 discharge moving heads. The last time I used all 4 was about 5 years ago. I did use 2 of them about 18 months ago. The rest of the time they sit in their boxes waiting for their next electrical safety test. Then go back in until the next one lol! I have many legnths of truss, winchstands and all sorts of gear that I never, ever use!
Try to buy smart and just buy once. It can be really hard but you'll get lots of advice on here