So much to unwrap here. Everyone's comments are valid but we are all in our own areas and what works for one person in one area, might not work for another.
Step 1.
Like any business you have risks and rewards, if you haven't already I would sit down and work out what you want to earn in wage, what your overheads are (or estimate them to be) and then you can work out how many days you need to work to cover your costs and potentially what your profit might be. Then compare your daily rate to others in the area. Call them up, don't pretend to be a customer. Just ask saying you are also looking to start up and don't want to undercut them. You never know, they might be flat out and offer you some work to get you started? Its happened to me and I've done it to others so don't think I'm crazy. Or they could tell you to f**k off but that's always the fun part and they wont be much competition if they say that.
Essentially this is a form of business plan and you should have a good idea by the end of what you need to earn (I say NEED not want) what your costs are and what your profit might be (profit is separate from your wage - wages are cost) You can do this for any size machine you like, and see how they compare.
Step 2.
Having worked out what your overheads are, find out what your market is. This is much harder as you have to kind of take a guess where you think your customers will come from. But mull it over and see if you cant work for as many kinds of people as possible. I work for private people, builders, landscapers, schools, local parish council, farmers, Heathrow airport, hospitals. Start off trying to appeal to as many as possible and narrow it down as you go. For example, I no longer work for people with Horses - its always trouble but you learn these things as you go.
Step 3. Knowing what your market is now you can work out how to tell them about who you are and what you offer. Personally I have never paid for marketing, I think you can be smart in the modern day about putting yourself in front of people. Come up with a name, simple logo/ branding then keep it consistent across your website, google business page, facebook business page, twitter, instagram, farmbackup, yell.com (free listings only- don't pay!) If necessary find other business like yours who's blurb you like and copy/ modify it to suit your business and style. Use some unique photos of work you might have done in your mums garden, or you've done at work before to get you started.
So far you have spent £0
Step 4.
Ask yourself if you really want to do this. Like really really. My business journey (well documented on here and the old CEF forum) has been the hardest thing I have EVER done. And I constantly ask myself (and Rory) if I should just give it up and work for someone. And I've made money! Some dont.....ever! You have to really want it. Want it so much you would work 14hrs a day 7 days a week for months on end. Not go out with your mates, not go on holiday, and when things go wrong or it rains when you're topsoiling, or a trench collapses, you have to be wanting it so much you laugh at your luck and keep dogging on the job into hour 15 on a Sunday evening. Then when you get home, write some invoices up and quote the next job. Nothing any of us can say on here will prepare you for what its like, but when it goes right, its the most satisfying feeling turning a job from a quote to a payment in your account.
Step 5.
Having passed step 4 you must be as crazy as the rest of us so welcome to the club! Now its the fun part, buying the machine! This is mandatory to open to discussion on the forum and the Bobcat and Takuchi reps will fight over who offers the cheapest finance and who has the most awkward nipple to grease. Things to note here though - VAT. Register for it and you have to charge it on top of your rate. This makes you expensive to private customers but is irrelevant to other contractors and commercial clients as they claim it back anyway. So if you have identified private clients as a big market in step 2, maybe think about swallowing the vat on the machine so you don't have to charge it. This might sway you away from new to maybe a tidy used machine to get you started? Finance (some on here have forgotten) is impossible to get when you first start on the sort of rates some of us enjoy now. All play a part in your decision.
Step 6.
Now get to work! You will be surprised the phone will start to ring from your various online pages. Obviously very slow at first. Personally I would try and get started while you still have some employment, just say you are busy and can only do a weekend if someone calls (which is technically true). Weekend work build experience, brings in some cash, and gives you a start before you have to rely on the income.
I could go on here, there's so many lessons I've learnt the hard way. And if you're truly committed there's nothing that would put you off anyway. And you need that naivety to take the leap in the first place! Good luck and hope something of what I have written above is helpful to you. Ill leave it to Eric Cartman to summarise.