This well-reviewed electric sit/stand desk is down to £116 at Amazon UK
This 120x60cm desk can support up to 80kg.
Want a cheap and cheerful standing desk for working or PC gaming? This electric option from Songmics has been reduced to £116 when you tick the £20 voucher on the product page and has plenty of five-star reviews, making it a good value pickup.
I've used a standing desk not much more expensive than this for years (from Flexispot, for the record) and it's served me well - I think these sorts of electric motors are now pretty much a solved problem, and even commodity examples like these are strong and reliable.
This desk even comes with a more advanced set of controls, allowing you to record up to four preferred heights between 72 and 120cm, so you can set up the desk at a comfortable height for you and one other person when both sitting and standing - a nice touch. There's also a numerical read-out to let you see the current height at a glance.
The table-top is relatively compact at 120x60cm, but still sufficient for a dual-monitor setup with a rated weight allowance of 80kg. The top of the desk is made of four pieces joined together, which is a little unusual but does allow for a comfortable front and centre section, a plain wood rear centre section and two side sections, each with a circular aperture - presumably used for a straight-through monitor mount or a cable routing channel.
This seems like a fine option for the money, and well worth considering at the current discounted price. (If you're interested in pricier alternatives, I wrote about some options over at Eurogamer, including the Ikea Idasen, Flexispot EQ4 and Herman Miller Nevi.)