Apart from window cleaning do you have any other businesses ?
I have a small unit in an emporium where I sell antiques, collectables and vintage items, I obtain my stock from auctions then clean them up and re-sale in my unit for a profit.
The unit costs me £252 per month but makes me between £800 - £1000 plus per month and I enjoy the buzz from buying and selling.
The good thing about this system is I don't have to be at the unit (only go there to restock ) they take the money for me and pay it into my bank, using my phone it tells me what I have sold and how much I've made on a daily basis.