There is no high-income restriction on contributing to a traditional IRA. Only the possible tax deduction is limited, however earnings on any contribution are still fully tax deferred.

>, you won't be able to sell that in any year where you make income above 40K because of "capital gains"

Let's clarify: for U.S. tax purposes, if your taxable income (which is much lower than gross income) as a single filer is below about $40K (double that if married filing jointly), your tax rate on long term capital gains is zero (for now). But even if you go over that, you still receive a highly favorable rate of only 15%, it doesn't go higher than that until taxable income gets up around $450K, so if you must sell with a gain, it's still quite tax-friendly. (Unfortunately, some states such as California have no special capital gains tax rate).