I have flaring nostrils and a hanging columella. What would it cost/how difficult would it be to correct this? (photos)

To begin with, hanging columella DOES NOT exist (except for very
elder and heavy noses), it is incorrect to attribute the "ptosis" or
droopiness to what should be called columellar exposure / show, excess
of visibility, septal mucosa exposure / show, but never like "hanging",
since it is not an ongoing or progressive process, it is just an
anatomcal feature of stable situation.

Columellar excess of visibility can be cause by different factors, of
greater or lesser contribution on each of such cases, like: alar rim
retraction or vertical shorfall, oversized thickness of medial cruras,
prominent caudal septum, oversized too long lateral cruras, sebaceous
skin, etc; on each case the treatment has to be customized to address
the specific underlying causes to the columellar exposure.
Yours seem to have as main cause the overly short vertical length of
the alae, aka alar rim retraction but better said shortness of alar rims
in vertical fashion, leading to exposure of the septal mucosa and the
columella. As secondary factor I detect an slight oversizing of the
infratip lobule.
The treatment I recommend in your case is, mainly, lateral crura
caudal extension batten grafts to lower the alar rims and thus supply
the missing "curtain" to cover the septum and the columella; additionaly
you need to sink in very very slightly the columella by means of a very
cautiously practiced tonghe-in-groove securization of the medial cruras
to the caudal septum. 
Under NO circumstances you should admit trimming the caudal septum,
that is the "easy way" for surgeons with poor understanding / skills
about exposed collumellas and retracted nostrils; by doing a caudal
septum trim you'd get a grotesque piggy nose.
Composite graftings are not very reliable, I don't like them at all,
they are also "easy" but unpredictable, you can't test them, you can't
fix them with suture, etc; it is way better (and also more complex)
direct visualization, intraop unlimited and versatile testing of the
lower push required and finally fixing and securing in place the grafts
with sutures.

Regarding your wish pic I can tell you is is feasible, by means of advanced techniques of tip plasty, eventually Sheen's graft.Difficulty 8 out of 10 in primary rhinoplasties, surgical time 3-4 hours.
If you wish better grounded opinion please do post or send privately
well lit, focused and standard images: frontal, both lateral and both
oblique views, also underneath the nostrils.
Feel free to request any additional information from me.

You have more of a retracted ala than a hanging columella.  A cartilage graft can be used to fix this.  In addition your tip is bulbous and slightly inferiorly rotated.  This can be fixed with sutures and reduction of cartilage.  

You appear to be relatively spot on for your analysis of your nose. You also appear to have a bit of a wide bulbous tip and I suspect that the cartilages that are forming it are overly rotated which is forcing your tip down and your ala to appear retracted resulting in the flaring that you describe. A rhinoplasty procedure with redirection of your ala to a more normal position with a technique that will raise your tip should help to correct your problem and give you the desired result. The approximate costs of the procedure in our area is about 5500 dollars. Good luck in your area.