There is not much time left.
If asked how much it is worth, I would be at a loss for an answer.
どれほど is a standard way to ask 'how much' or 'to what extent', while 幾ばく carries a more formal, sometimes archaic tone.
Mixed kanji-kana spelling; usually written in kana.
Kana spelling is the most common and recommended for learners.
Full kanji form; rarely used in modern writing.
Rarely used kanji form; easily confused with 幾何 (きか, geometry).
Compound of 幾 (iku, 'how many') + ばく (baku, an old suffix indicating amount or degree). The suffix ばく is of uncertain origin but appears in classical Japanese.