Start with the offer
Write down one specific result, the customer who needs it and what a small first version will include. For example, instead of buying an industrial mixer because you hope to sell cakes, decide that you will offer six-inch birthday cakes to working parents in your area. Create one sample, use a mock-up or borrow suitable equipment for the test. Do not confuse excitement about the equipment with evidence that people want the result it produces.
Speak to likely customers
Contact about ten people who genuinely fit the customer description. Ask how they currently solve the problem, what frustrates them, what they normally pay and when they would need an alternative. A neighbour saying “This is a lovely idea” is encouraging, but it is not the same as asking for a price or delivery date. Avoid questions that invite politeness, such as “Would you support my business?” Ask about real behaviour instead.
Run a small paid test
Offer a limited first service or preorder with a clear scope, price and date. A prospective laundry operator might collect five confirmed orders and use a trusted local laundry for the first round before buying a washing machine. A phone-accessory seller could show supplier photographs, take orders for two or three clearly described items and buy only confirmed quantities. Explain honestly that it is a limited test, agree on what the customer will receive and avoid taking more orders than you can deliver well.
Use a decision rule
Decide in advance what evidence would justify the next expense. That might be three deposits, five paid orders, repeated requests for faster delivery or enough enquiries to cover a sensible part of the equipment cost. If people only like the idea but do not act, improve the offer, price or customer group before spending. If the test produces strong, repeated demand, compare renting, borrowing, buying used and buying new rather than automatically choosing the most expensive option.