Dizzyjam Band Merchandise
Print and order on-demand music merchandise and t-shirt printing. You start earning money from your very first sale and you set your own product prices (and therefore profit margins), but if you choose to leave it at the default settings, you earn a massive £6.25 if you sell a hoodie, £3.75 on every t-shirt. ($10 and $5 if the sale is in the USA). Sell just 135 shirts and that's over £500 in your pocket for no outlay.