If you LITs are DRM-free then Calibre (has its own forum here) can convert them to MOBI or ePub or LRF. This means that they will work well on all mainstream EInk Readers. If they have DRM, then ConvertLIT can strip the DRM, and it runs on the Mac once you get a key from your Windows PC running MS Reader. If you are not willing to strip DRM (which is thought by some to be illegal in the US) then your DRMed LITs are boat anchors so far as dedicated reqading devices are concerned.
If you eyesight is really bad, then the Cybook may be your best bet, see
E-Reader with Biggest Text Size?. However, I suggest waiting until the current MOBI vs ePub issue is sorted out at Bookeen (probably by next week). If your eyesight is only poor, then any EInk Reader is probably ok. You may need a stronger light than for reading paperbacks, but usually it is enough to increase the font size in low light.
Amazon does not charge for your own ebooks if you transfer them to the Kindle by USB (the charge, which is now $0.15 per MB, is for wireless download). It only reads MOBI, but Calibre can create those for you. The Kindle's big advantage is the Kindle Store, which is the best single source for US-licensed ebooks. If you want maximum buying convenience the Kindle is the only choice, but it is expensive (Amazon's ebook prices are relatively low though).