Refractors divide into two products that share a shape: inexpensive two element achromats, which show a colour fringe on bright objects, and expensive three element apochromats, which do not. Almost every question about refractor prices is really a question about which of those you are looking at.
What the fringe is and when it matters
A single glass bends blue light more than red, so a simple lens focuses the colours at slightly different points. On the moon's limb or a bright star this appears as a violet halo. At long focal ratios it is faint enough to ignore, which is why traditional achromats are long. At the short focal ratios modern buyers want, it becomes obvious, and correcting it needs special glass.
What an apochromat costs
William Optics prints $498.00 for its cheapest apochromatic refractor, and that is the entry point rather than the middle. For comparison, this index carries a 114mm reflector at $91.00 on sale. The refractor gathers about a quarter as much light and costs five times as much, and neither figure is unreasonable: they are prices for different jobs.
What you get for it
A sealed tube that never needs collimation, no central obstruction so slightly higher contrast per millimetre of aperture, and a star image clean enough that a camera cannot find fault with it across a wide field. For photography that combination is worth the money; for looking at faint things, aperture bought elsewhere wins easily.
Questions people ask about telescope
What does apochromatic mean?
That the objective brings three wavelengths to a common focus using specialised low dispersion glass, so bright objects show no colour fringe. It is the main cost driver in a premium refractor.
Are refractors better than reflectors?
Per millimetre of aperture, marginally, on contrast. Per pound spent, no, because aperture is far cheaper in a reflector. Refractors win on maintenance, portability and photographic star quality.
How much does a refractor telescope cost?
Small achromats start below a hundred dollars; the cheapest apochromat in this index prints $498.00. The gap between those two figures is almost entirely the glass in the objective.