How to make a time-conditional price offer - Germany

I'm appealing to the general TT expertise for help in expressing two phrases in German. Unfortunately I can't even manage to say it exactly right in English ... maybe I'm getting mixed up with the languages.

Phrase 1
- my offer is open until the end of February
- my offer holds until the end of February
- my offer is valid until the end of February
- I'm interested in buying X until the end of February

Phrase 2
.. after February I am no longer interested
... after February my offer is withdrawen

Any help is very much appreciated!

As Freddie Frinton says at the end of the "Dinner for One" sketch...I shall do my very best!

I`m not quite sure on the Capital letters or the "Mein/Meinem" form - I`m sure someone here on TT will correct me.

Phrase 1.

Mein Angebot halte ich bis Ende Februar offen.

Mein Angebot steht bis Ende Februar

Mein Angebot ist bis Ende Februar gültig.

Ich habe interesse bis Ende Februar XXXX zu erwerben/kaufen.

Phrase 2.

Ab Ende Februar habe ich keine interesse mehr.

Mein Angebot ist ab Ende Februar nicht mehr gültig.

"Mein Angebot steht bis Ende Februar" is great, but - being of the legal persuasion myself - I would name a specific date, i.e. "steht bis 29. Februar 2008".

"Nach dem Ablauf des Februar besteht kein Interesse mehr" is more precise than "Ende Februar".

Angebot gilt bis (date goes here) would be the usual expression here. No frills, no need for a definite or indefinite article at the beginning, no need to say "mine", "this" or anything else. Simply (eg) Angebot gilt bis 27. Juli 2008.
Phrase 2 is unnecessary as the offer shown ceases to have any relevance after ther terminal date but if you'd feel happier with a further statement then simply change to "Gilt bis (27. Juli), danach enfällt mein Angebot.", making one sentence of it.

I second that. In fact it's the only correct expression. Angebot gilt bis... Angebot ist gültig bis...

"Danach entfällt mein Angebot" isn't necessary, because it becomes clear in the first statement anyway.

All the other examples aren't proper German, you wouldn't say that.

excellent stuff, thanks all for your help