John I'm at the lower end of your target. My normal advertising budget is £360 per annum. £138 is the only proper advertising I do (YP Corporate Advert with NCCA in two directories). The rest is community advertising which I do expecting no return. I've never had a response from the local football club programme in over 10 years!. Being a member of the NCCA, I receive considerably more work from their website and office referal system than the cost of my annual fees. I don't cost this as paid advertising, just a benefit of membership.
This year I also got involved with a local theatre production to the tune of £300, again expecting nil return. So you could say that my advertising has gone up this year from about £7 per week to <£13 per week

Advertising/direct marketing is a choice rather than a necessity.
I'm blessed with an established business whereby I don't need to be involved with direct marketing. I have to ask myself if I want to spend a few £k's do generate a few £k's more or use my time for other things.
There are however, no/low cost ways to market your business. The first is best explained in a phrase I coined many years ago. Kitchen Sink Marketing. This is where you spend more time with your customer rather than a quick in/out so you can fit more jobs in a day. Obviously you will need to be towards the premium end of pricing, but you also need to give more. Apart from the social aspect of "kissing the cat and kicking the kids" talk through good housekeeping procedures. Such as how to vac, how to care for the machine, how to treat spillages, spotting techniques and products, walking off detergent residues from kitchen floors etc. etc. If, like me, you are the sort of person who receives greater pleasure from working this way rather than a salesmans pleasure from just making the sale, then this is an avenue to be explored. It's what works for me and also valued colleagues such as the Bolton Brothers and others whose names you may not be too familiar with. I also have a good working, and personal, relationship with quality local carpet retailers and a local radio consumers affairs broadcaster.
Unfortunately, you may need to market yourself aggressively to reach this stage of comfort.
Safe and happy cleaning

Ken