To get to the point, she's going to get a degree in music at college and is embarrassed to bring the Venus horn - it's been great for her to try Soprano but she wants a quality horn. Curved sopranos are not cheap as you all know. I'm wondering what you all advise.
It’s a long time in but Did you buy another one? If she tries it against things 10x as expensive and she prefers her cheap one and sounds good on it why not be proud to have such a bargain for something that plays well. There would be no point buying something which is less easy to play and/or sounds worse just because it has big brand name and costs more.
She can probably make anything that is functioning sound good and indeed you said she makes a Venus sound better than her posher brand alto and tenor. If two instruments sound as good but one is nicer to play it wins. If a genuinely better instrument comes up and fulfils the need to look serious by possessing a pro instrument, given how well she plays the Venus why not keep it as a back up / travel instrument as well as she clearly gets on with it (if finances allow an expensive and a cheap one).
It can also be as “cool” to play a vintage instrument as it is to play a modern Selmer, Yanigasawa, Yamaha, R&C etc. The current pro brands are also cheaper second hand and keep their value with less depreciation for resale.
So she could try some vintage Selmers / Conn / Martin etc.
I have a Yamaha alto and Selmer tenor but when it comes to Soprano and baritone I have Chinese made Bauhaus Walstein (BW) and I can honestly say I have tried them against big brands and either found my BWs better or insufficiently different to tell. I originally owned a Yanagisawa curved soprano and tried it against a BW curved in a shop and the BW was better. I took my Yani to a different shop and got it serviced and then went back and tried it against the BW again. The BW was still better than the serviced Yani. I bought the BW and sold the Yani for nearly three times the cost of the BW. So I had a better instrument and the money to buy two more if I felt the need. I have since tried it against PMauriats and Yamahas and have stuck with it. The Bari similarly before replacing my low Bb 1932 Kohlert I tried a Yamaha 32, 62 Yani 901, a Howarth Chiltern, a Buffet and a John Packer Cadence and it a BW was best.
So she should try a few out and stick with the best one to play in terms of sound and build/ mechanism