Prom dress help

[Pentiumgold]

Am I the only parent shocked at the prices being paid for prom dresses? And that's without the shoes, bag, nails, tan and makeup!!
I cannot afford to pay what seems to be between £245 and £350 for a dress.
Thankfully dd realises this but is struggling to find decent cheaper alternatives.
She wants a fitted long dress in Royal blue with a criss Cross design on the back.
Any suggestions please?

Have you both looked on the Vinted app?

New and once worn dresses. All sorts of prices, some really inexpensive because they are high street brands, some more expensive but designer.

This has a crossed back, this is just one, I filtered by colour there are hundreds of blue dresses.

www.vinted.co.uk/women/clothes/dresses/special-occasion-dresses/prom-dresses/1521506604-dynasty-occasionprom-dress 

Remember you can make a lower offer to sellers. Postage has to be paid for too.

I'm not really shocked at the prices from the bridal/prom dress shops, but I am shocked that it seems to be the done thing to get a dress of this type rather than just any posh dress from a normal shop. I've only started looking online after a few threads on MN, and I naively thought that there would be a mixture of dresses worn by the girls in our fairly working class area - but looking into it it seems they nearly all go for the very formal, long style.
Anyway after doing lots of research over the last few days, I remember seeing something similar to what you are after: this links to an image in navy, but the option is in royal blue (it was either this dress I saw or something very similar in the customer gallery).
www.jjshouse.co.uk/Sheath-Column-V-Neck-Floor-Length-Satin-Prom-Dresses-With-Pleated-018268688-g268688?pos=similar_styles_1

There are other places to order from online too, Ebay is one, let me know if you want the link to a seller I found, they definitely do royal blue but not sure about the criss cross back.

Dd bought her prom dress from Quiz. It cost about £80. They don't seem to have anything that fits your daughter's exact colour scheme/idea but they do have lots of nice dresses.

There are tons of them on next or chichi clothing or quiz. EBay is another source, I've just bought my Dds from there. Lots of people are advertising second hand (sometimes not even worn ones because of the last two years getting cancelled) on our local Facebook selling page. Our local BHF charity shop collects them and does a big prom dress display so check if there's anything like that. And finally, the school here also collects donations of dresses and suits and lend them out to pupils who otherwise couldn't afford them. Lots of avenues to investigate!

My dd found dozens she likes for under £100 on Asos.

New Look are good for shoes/clutch bags.

Loads on Ebay for £20. You could have it altered and dry cleaned all for a reasonable price.

Thank you all for your suggestions- am off to Google now