Apple Inc. (NASDAQ:AAPL)’s iPhone 6 and 6 Plus have been in the market for almost three months. But the demand for new iPhones is so strong that Apple is still facing supply constraints for higher storage variants of the iPhone 6 and 6 Plus. A recent survey conducted by Canaccord Genuity indicated that the strong demand will lead to higher average selling prices (ASP) and bigger profits for the Cupertino company.

iPhone 6 top selling device in the U.S.

Canaccord Genuity analyst Michael Walkley (via AppleInsider) said in a research note Tuesday that findings of his November smartphone survey show that the 64GB and 128GB are still difficult to find in stores. Walkley has raised his price target on Apple to $135. Continued demand for higher storage models will increase the ASP to $700. The research firm expects Apple to ship 63 million units in the current quarter.

Canaccord Genuity’s survey revealed that the iPhone 6 was the highest selling smartphone on all of the top four U.S.carriers in November – Verizon, AT&T, T-Mobile and Sprint. The 5.5-inch iPhone 6 Plus occupied the second rank, followed by Samsung’s Galaxy Note 4. Further, the research firm surveyed 75 AT&T stores on Nov.26.

Apple iPhone 6

64GB iPhone 6 most popular among consumers

It found that 44% of those stores had the 16GB iPhone 6 in stock. But only 8% of them had the 64GB model, and none of them had the 128GB iPhone 6. Store executives from the top four carriers told Canaccord Genuity that the 64GB version was the most popular among consumers. Wait time for higher storage models is a few weeks, depending on the carrier.

Walkley forecasts FY2015 earnings of $8.50 per share. He added that consumer preference for more expensive, higher capacity iPhone models will continue in the future. In the third quarter of this year, Apple dominated 86% of the smartphone industry profits. The only other major smartphone vendor earning a profit on its devices is Samsung, whose Q3 profits tumbled more than 60%.

Apple shares fell 0.43% to $114.14 in pre-market trading Wednesday.