They can give you up to $10,000 each tax free as a gift. (that number may have gone up). Let them give 9,800 each per year to you as a gift and pay personal income taxes on the rest. Then either grant them stock or options or convertible debt on the rest. If you are using the money to "pay" yourself you are supposed to declare it as income. And they need to show "consideration" for their investment for it to be truly an investment. Even if it is only $200 per month. At least that is the way I understand the tax code but I am not an accountant or a lawyer. Just an entrepreneur.
Personally I think placing a value on a company, even at the beginning is always best and most fair. The early investors take the most risk and should get stock at the best value. If they have to wait until an angel or a VC puts a value on it, they effectively get penalized by that valuation, typically higher than the value at the early seed stage. I try to avoid convertible notes both as an angel and as an entrepreneur.