Apple Inc. is widely expected to unveil its next-generation iPhones at an event Tuesday, including a cheaper version that one analyst says could give a boost to the struggling stock price.

WSJ has reported Apple is expected to unveil a cheaper model that could come in a variety of colors as well as a new high-end phone. Both those phones are expected to begin shipping from manufacturers in early September.

The low-priced version could be especially crucial to the company's top and bottom lines. Toni Sacconaghi, senior analyst at Sanford C. Bernstein, forecasts the low-end smartphone market will grow to about 900 million units by 2015. His back-of-the-envelop math suggests if Apple could capture 10% of that market share (compared to the 45% share it commands of the high-end market), the company could generate another $30 billion in incremental revenue. And a cheaper iPhone could lead to 'mid-to high-single digit percent' earnings growth in fiscal 2015, he added.

'Our positiveinvestment opinion on Apple is predicated on our belief that innovation continues to persist at the company,' Mr. Sacconaghi said in a note to clients on Monday, 'and that new products can ultimately drive upward revisions and an improved multiple.

'Chief among these new product opportunities is a lower-priced iPhone.'

He expects the cheaper iPhone to be priced around $400, roughly in-line with many of the media reports over the past several risks. 'The higher [average selling price] will lower demand, but also blunts some of the negative gross profit [margin] impact.'

So how does all of that impact Apple's stock price, which despite the recent leg up is still underperforming the broad market for the year. Here's Mr. Sacconaghi's take:

'Apple's stock has historically moved in tandem with earnings revisions. We believe Q4 and FY14 earnings estimates are now at reasonable levels, and note that we (and likely consensus) estimates do not appear to include a lower priced iPhone. Give a favorableestimateoutlook backdrop and an attractive valuation...we believe the risk/reward for owning Apple is currently favorable, and rate the stock outperform with a $600 price target.'

Apple shares recently rose 1.6% to $506.32 and are up 28% since the end of June. Even amid the recent rally, the stock remains down 4.9% for the year, compared to a 16% year-to-date rally for the S&P 500.