How long after did the buyer booked the lot from when the offer was made? I have learned that in new construction, if you do not perform quickly, prices may change. 

I'm assuming when the offer of $5,000 off was made, it was provided in writing somewhere. If there's no expiration date on that documented offer, then they should honor their offer.

First question... how much time has passed between the offer and the acceptance of the promotion and did it have an ending date. If it's 24 hours, I'd be yelling and screaming till I got for my client. If it's days or weeks, tough luck. Snooze, you lose.

If the promotion is still listed in MLS as it was, then it applies.

If it wasn't in MLS, I'd offer (aloud) to the buyers to go back to 'the other' community and work with a builder who stands by their promises.

That's why I'm glad everything new construction in my market is represented by an agent and in the MLS.  If an "offer" has an expiration they are required to put that information in the MLS and as a BA I would have known prior to presenting to my buyer.

I would still have them honor the promotion.

If there is no expiration date anywhere where promotion is mentioned they have to honor it. Did they present any document that it is expired? I usually attach MLS printouts on the moment of submitting offer, so what ever terms there, a listing agent can not change( they try to change commission sometimes).

Can he show you proof that offer has expired?  

Make an offer.

Praful Thakkar Have to read the fine print.

Kat Palmiotti nailed this one!

How do you spell fraud

Sometimes those promotions are for a specific timeframe, did you go past it?   Is your market strong, maybe you can negotiate with the builder.

Was there anything in writing? Among the most important (and ignored) items in all contracts are DATES. Also clauses like "time is of the essence", when you have to perform within the time parameters specified. Leaving things open-ended leads to confusion and possible disputes.

WEll you can complain ro move on and I wold move on to a different builder.

Ask if they will honor it unless they told you the price weeks ago and then the problem is you waited too long.

Can you get a copy of the promotion with the expiration date?

I work for a builder and yes promotions do expire! Also, most builders have a disclaimer in the fine print that promotions can expire anytime. We always post when a promotion expires or we tell prospects if prices are going to go up, though the sales agent does not always know.

What does MLS say?  Is there an expiration date noted on this offer?

Submit the offer and if they want to be deceptive then move on.

If there was no expiration date on the offer, fight for it!

Not enough information here (details) Praful to respond.  It leaves me with more questions to get the facts. 

Accept it. 

I use to see Friday newpaper advertising for special deal and find next day these promotion is waiting for me. After lost out I have the check ready and go there Friday calling home what color you want? They have black and white is already taken at 9 AM..... 

if the home is finished, submit what was quoted...

if the home is still under construction, eliminate it...you'll be paying that $5k and more with items that should be minimal costs... the builder will have a fund raiser with your extras...

 My offer is expired.  On to the next one!

In Real Esate one must move with a purpose. Many ways to find that out

Is the builder using an employee in their sales office or a licensed real estate agent?  

The protocol for the licensed agent is well established.

But the employee...well, it is time to see your negotiation skills put to the test.

Was it in writing?

If not it never happend, if so there should be an expiration in there somewhere

I ask to go direct to the builder. Someone made a mistake, I'd find out who for my buyer.

Always get it in writing. Then make the offer, include a letter to the builder and see what they say

Ask to talk to the builder directly and ask him how much he cares about his reputation.

Prices are subject to change without notice. Not a great practice but often done. You snoze, you lose! In a tight market, they can get away with it!